- Instead of forcefully adding

    -Wall
    -Wextra
    -Wno-unused
    -Wcast-qual
    -Wcast-align
    -Wbad-function-cast
    -Wmissing-declarations
    -Wmissing-prototypes
    -Wnested-externs
    -Wredundant-decls
    -Wshadow
    -Wwrite-strings
    -Wundef
    to CFLAGS, 'configure' now tests if the flags are understood by the compiler


git-svn-id: svn://svn.ircd-hybrid.org/svnroot/ircd-hybrid/branches/8.1.x@2492 82007160-df01-0410-b94d-b575c5fd34c7

14 files changed, 1122 insertions, 2 deletions

diff --git a/Makefile.in b/Makefile.in
index d10d1de..5d7ec26 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -85,6 +85,9 @@ DIST_COMMON = $(srcdir)/Makefile.in $(srcdir)/Makefile.am \
 	ylwrap ltmain.sh
 ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
 am__aclocal_m4_deps = $(top_srcdir)/m4/argz.m4 \
+	$(top_srcdir)/m4/ax_append_compile_flags.m4 \
+	$(top_srcdir)/m4/ax_append_flag.m4 \
+	$(top_srcdir)/m4/ax_check_compile_flag.m4 \
 	$(top_srcdir)/m4/ax_check_openssl.m4 \
 	$(top_srcdir)/m4/gcc_stack_protect.m4 \
 	$(top_srcdir)/m4/libtool.m4 $(top_srcdir)/m4/ltdl.m4 \
diff --git a/acinclude.m4 b/acinclude.m4
index 556b28f..1a0a046 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -147,7 +147,19 @@ dnl {{{ ax_arg_enable_warnings
 AC_DEFUN([AX_ARG_ENABLE_WARNINGS],[
   AC_ARG_ENABLE([warnings],[AS_HELP_STRING([--enable-warnings],[Enable compiler warnings.])],[warnings="$enableval"],[warnings="no"])
   if test "$warnings" = "yes" ; then
-    CFLAGS="-Wall -Wextra -Wno-unused -Wcast-qual -Wcast-align -Wbad-function-cast -Wmissing-declarations -Wmissing-prototypes -Wnested-externs -Wredundant-decls -Wshadow -Wwrite-strings -Wundef"
+    AX_APPEND_COMPILE_FLAGS([-Wall])
+    AX_APPEND_COMPILE_FLAGS([-Wextra])
+    AX_APPEND_COMPILE_FLAGS([-Wno-unused])
+    AX_APPEND_COMPILE_FLAGS([-Wcast-qual])
+    AX_APPEND_COMPILE_FLAGS([-Wcast-align])
+    AX_APPEND_COMPILE_FLAGS([-Wbad-function-cast])
+    AX_APPEND_COMPILE_FLAGS([-Wmissing-declarations])
+    AX_APPEND_COMPILE_FLAGS([-Wmissing-prototypes])
+    AX_APPEND_COMPILE_FLAGS([-Wnested-externs])
+    AX_APPEND_COMPILE_FLAGS([-Wredundant-decls])
+    AX_APPEND_COMPILE_FLAGS([-Wshadow])
+    AX_APPEND_COMPILE_FLAGS([-Wwrite-strings])
+    AX_APPEND_COMPILE_FLAGS([-Wundef])
   fi
 ])dnl }}}
 dnl {{{ ac_define_dir
diff --git a/aclocal.m4 b/aclocal.m4
index 48ea48f..e4015ab 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -1202,6 +1202,9 @@ AC_SUBST([am__untar])
 ]) # _AM_PROG_TAR
 
 m4_include([m4/argz.m4])
+m4_include([m4/ax_append_compile_flags.m4])
+m4_include([m4/ax_append_flag.m4])
+m4_include([m4/ax_check_compile_flag.m4])
 m4_include([m4/ax_check_openssl.m4])
 m4_include([m4/gcc_stack_protect.m4])
 m4_include([m4/libtool.m4])
diff --git a/configure b/configure
index d7b6d05..3fe7183 100755
--- a/configure
+++ b/configure
@@ -14504,6 +14504,63 @@ fi
     CFLAGS="-Wall -g -O0"
   fi
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts " >&5
+$as_echo_n "checking whether C compiler accepts ... " >&6; }
+if ${ax_cv_check_cflags__+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  "
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  ax_cv_check_cflags__=yes
+else
+  ax_cv_check_cflags__=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_check_cflags__" >&5
+$as_echo "$ax_cv_check_cflags__" >&6; }
+if test x"$ax_cv_check_cflags__" = xyes; then :
+  :
+else
+  :
+fi
+
+if ${CFLAGS+:} false; then :
+  case " $CFLAGS " in
+    *"  "*)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS already contains "; } >&5
+  (: CFLAGS already contains ) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      ;;
+    *)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS=\"\$CFLAGS \""; } >&5
+  (: CFLAGS="$CFLAGS ") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      CFLAGS="$CFLAGS "
+      ;;
+   esac
+else
+  CFLAGS=""
+fi
+
 
   # Check whether --enable-warnings was given.
 if test "${enable_warnings+set}" = set; then :
@@ -14513,7 +14570,825 @@ else
 fi
 
   if test "$warnings" = "yes" ; then
-    CFLAGS="-Wall -Wextra -Wno-unused -Wcast-qual -Wcast-align -Wbad-function-cast -Wmissing-declarations -Wmissing-prototypes -Wnested-externs -Wredundant-decls -Wshadow -Wwrite-strings -Wundef"
+
+
+for flag in -Wall; do
+  as_CACHEVAR=`$as_echo "ax_cv_check_cflags__$flag" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts $flag" >&5
+$as_echo_n "checking whether C compiler accepts $flag... " >&6; }
+if eval \${$as_CACHEVAR+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  $flag"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  eval "$as_CACHEVAR=yes"
+else
+  eval "$as_CACHEVAR=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+eval ac_res=\$$as_CACHEVAR
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+if test x"`eval 'as_val=${'$as_CACHEVAR'};$as_echo "$as_val"'`" = xyes; then :
+  if ${CFLAGS+:} false; then :
+  case " $CFLAGS " in
+    *" $flag "*)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS already contains \$flag"; } >&5
+  (: CFLAGS already contains $flag) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      ;;
+    *)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS=\"\$CFLAGS \$flag\""; } >&5
+  (: CFLAGS="$CFLAGS $flag") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      CFLAGS="$CFLAGS $flag"
+      ;;
+   esac
+else
+  CFLAGS="$flag"
+fi
+
+else
+  :
+fi
+
+done
+
+
+
+for flag in -Wextra; do
+  as_CACHEVAR=`$as_echo "ax_cv_check_cflags__$flag" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts $flag" >&5
+$as_echo_n "checking whether C compiler accepts $flag... " >&6; }
+if eval \${$as_CACHEVAR+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  $flag"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  eval "$as_CACHEVAR=yes"
+else
+  eval "$as_CACHEVAR=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+eval ac_res=\$$as_CACHEVAR
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+if test x"`eval 'as_val=${'$as_CACHEVAR'};$as_echo "$as_val"'`" = xyes; then :
+  if ${CFLAGS+:} false; then :
+  case " $CFLAGS " in
+    *" $flag "*)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS already contains \$flag"; } >&5
+  (: CFLAGS already contains $flag) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      ;;
+    *)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS=\"\$CFLAGS \$flag\""; } >&5
+  (: CFLAGS="$CFLAGS $flag") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      CFLAGS="$CFLAGS $flag"
+      ;;
+   esac
+else
+  CFLAGS="$flag"
+fi
+
+else
+  :
+fi
+
+done
+
+
+
+for flag in -Wno-unused; do
+  as_CACHEVAR=`$as_echo "ax_cv_check_cflags__$flag" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts $flag" >&5
+$as_echo_n "checking whether C compiler accepts $flag... " >&6; }
+if eval \${$as_CACHEVAR+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  $flag"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  eval "$as_CACHEVAR=yes"
+else
+  eval "$as_CACHEVAR=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+eval ac_res=\$$as_CACHEVAR
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+if test x"`eval 'as_val=${'$as_CACHEVAR'};$as_echo "$as_val"'`" = xyes; then :
+  if ${CFLAGS+:} false; then :
+  case " $CFLAGS " in
+    *" $flag "*)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS already contains \$flag"; } >&5
+  (: CFLAGS already contains $flag) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      ;;
+    *)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS=\"\$CFLAGS \$flag\""; } >&5
+  (: CFLAGS="$CFLAGS $flag") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      CFLAGS="$CFLAGS $flag"
+      ;;
+   esac
+else
+  CFLAGS="$flag"
+fi
+
+else
+  :
+fi
+
+done
+
+
+
+for flag in -Wcast-qual; do
+  as_CACHEVAR=`$as_echo "ax_cv_check_cflags__$flag" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts $flag" >&5
+$as_echo_n "checking whether C compiler accepts $flag... " >&6; }
+if eval \${$as_CACHEVAR+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  $flag"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  eval "$as_CACHEVAR=yes"
+else
+  eval "$as_CACHEVAR=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+eval ac_res=\$$as_CACHEVAR
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+if test x"`eval 'as_val=${'$as_CACHEVAR'};$as_echo "$as_val"'`" = xyes; then :
+  if ${CFLAGS+:} false; then :
+  case " $CFLAGS " in
+    *" $flag "*)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS already contains \$flag"; } >&5
+  (: CFLAGS already contains $flag) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      ;;
+    *)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS=\"\$CFLAGS \$flag\""; } >&5
+  (: CFLAGS="$CFLAGS $flag") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      CFLAGS="$CFLAGS $flag"
+      ;;
+   esac
+else
+  CFLAGS="$flag"
+fi
+
+else
+  :
+fi
+
+done
+
+
+
+for flag in -Wcast-align; do
+  as_CACHEVAR=`$as_echo "ax_cv_check_cflags__$flag" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts $flag" >&5
+$as_echo_n "checking whether C compiler accepts $flag... " >&6; }
+if eval \${$as_CACHEVAR+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  $flag"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  eval "$as_CACHEVAR=yes"
+else
+  eval "$as_CACHEVAR=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+eval ac_res=\$$as_CACHEVAR
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+if test x"`eval 'as_val=${'$as_CACHEVAR'};$as_echo "$as_val"'`" = xyes; then :
+  if ${CFLAGS+:} false; then :
+  case " $CFLAGS " in
+    *" $flag "*)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS already contains \$flag"; } >&5
+  (: CFLAGS already contains $flag) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      ;;
+    *)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS=\"\$CFLAGS \$flag\""; } >&5
+  (: CFLAGS="$CFLAGS $flag") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      CFLAGS="$CFLAGS $flag"
+      ;;
+   esac
+else
+  CFLAGS="$flag"
+fi
+
+else
+  :
+fi
+
+done
+
+
+
+for flag in -Wbad-function-cast; do
+  as_CACHEVAR=`$as_echo "ax_cv_check_cflags__$flag" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts $flag" >&5
+$as_echo_n "checking whether C compiler accepts $flag... " >&6; }
+if eval \${$as_CACHEVAR+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  $flag"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  eval "$as_CACHEVAR=yes"
+else
+  eval "$as_CACHEVAR=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+eval ac_res=\$$as_CACHEVAR
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+if test x"`eval 'as_val=${'$as_CACHEVAR'};$as_echo "$as_val"'`" = xyes; then :
+  if ${CFLAGS+:} false; then :
+  case " $CFLAGS " in
+    *" $flag "*)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS already contains \$flag"; } >&5
+  (: CFLAGS already contains $flag) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      ;;
+    *)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS=\"\$CFLAGS \$flag\""; } >&5
+  (: CFLAGS="$CFLAGS $flag") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      CFLAGS="$CFLAGS $flag"
+      ;;
+   esac
+else
+  CFLAGS="$flag"
+fi
+
+else
+  :
+fi
+
+done
+
+
+
+for flag in -Wmissing-declarations; do
+  as_CACHEVAR=`$as_echo "ax_cv_check_cflags__$flag" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts $flag" >&5
+$as_echo_n "checking whether C compiler accepts $flag... " >&6; }
+if eval \${$as_CACHEVAR+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  $flag"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  eval "$as_CACHEVAR=yes"
+else
+  eval "$as_CACHEVAR=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+eval ac_res=\$$as_CACHEVAR
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+if test x"`eval 'as_val=${'$as_CACHEVAR'};$as_echo "$as_val"'`" = xyes; then :
+  if ${CFLAGS+:} false; then :
+  case " $CFLAGS " in
+    *" $flag "*)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS already contains \$flag"; } >&5
+  (: CFLAGS already contains $flag) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      ;;
+    *)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS=\"\$CFLAGS \$flag\""; } >&5
+  (: CFLAGS="$CFLAGS $flag") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      CFLAGS="$CFLAGS $flag"
+      ;;
+   esac
+else
+  CFLAGS="$flag"
+fi
+
+else
+  :
+fi
+
+done
+
+
+
+for flag in -Wmissing-prototypes; do
+  as_CACHEVAR=`$as_echo "ax_cv_check_cflags__$flag" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts $flag" >&5
+$as_echo_n "checking whether C compiler accepts $flag... " >&6; }
+if eval \${$as_CACHEVAR+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  $flag"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  eval "$as_CACHEVAR=yes"
+else
+  eval "$as_CACHEVAR=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+eval ac_res=\$$as_CACHEVAR
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+if test x"`eval 'as_val=${'$as_CACHEVAR'};$as_echo "$as_val"'`" = xyes; then :
+  if ${CFLAGS+:} false; then :
+  case " $CFLAGS " in
+    *" $flag "*)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS already contains \$flag"; } >&5
+  (: CFLAGS already contains $flag) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      ;;
+    *)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS=\"\$CFLAGS \$flag\""; } >&5
+  (: CFLAGS="$CFLAGS $flag") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      CFLAGS="$CFLAGS $flag"
+      ;;
+   esac
+else
+  CFLAGS="$flag"
+fi
+
+else
+  :
+fi
+
+done
+
+
+
+for flag in -Wnested-externs; do
+  as_CACHEVAR=`$as_echo "ax_cv_check_cflags__$flag" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts $flag" >&5
+$as_echo_n "checking whether C compiler accepts $flag... " >&6; }
+if eval \${$as_CACHEVAR+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  $flag"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  eval "$as_CACHEVAR=yes"
+else
+  eval "$as_CACHEVAR=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+eval ac_res=\$$as_CACHEVAR
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+if test x"`eval 'as_val=${'$as_CACHEVAR'};$as_echo "$as_val"'`" = xyes; then :
+  if ${CFLAGS+:} false; then :
+  case " $CFLAGS " in
+    *" $flag "*)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS already contains \$flag"; } >&5
+  (: CFLAGS already contains $flag) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      ;;
+    *)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS=\"\$CFLAGS \$flag\""; } >&5
+  (: CFLAGS="$CFLAGS $flag") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      CFLAGS="$CFLAGS $flag"
+      ;;
+   esac
+else
+  CFLAGS="$flag"
+fi
+
+else
+  :
+fi
+
+done
+
+
+
+for flag in -Wredundant-decls; do
+  as_CACHEVAR=`$as_echo "ax_cv_check_cflags__$flag" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts $flag" >&5
+$as_echo_n "checking whether C compiler accepts $flag... " >&6; }
+if eval \${$as_CACHEVAR+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  $flag"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  eval "$as_CACHEVAR=yes"
+else
+  eval "$as_CACHEVAR=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+eval ac_res=\$$as_CACHEVAR
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+if test x"`eval 'as_val=${'$as_CACHEVAR'};$as_echo "$as_val"'`" = xyes; then :
+  if ${CFLAGS+:} false; then :
+  case " $CFLAGS " in
+    *" $flag "*)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS already contains \$flag"; } >&5
+  (: CFLAGS already contains $flag) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      ;;
+    *)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS=\"\$CFLAGS \$flag\""; } >&5
+  (: CFLAGS="$CFLAGS $flag") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      CFLAGS="$CFLAGS $flag"
+      ;;
+   esac
+else
+  CFLAGS="$flag"
+fi
+
+else
+  :
+fi
+
+done
+
+
+
+for flag in -Wshadow; do
+  as_CACHEVAR=`$as_echo "ax_cv_check_cflags__$flag" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts $flag" >&5
+$as_echo_n "checking whether C compiler accepts $flag... " >&6; }
+if eval \${$as_CACHEVAR+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  $flag"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  eval "$as_CACHEVAR=yes"
+else
+  eval "$as_CACHEVAR=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+eval ac_res=\$$as_CACHEVAR
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+if test x"`eval 'as_val=${'$as_CACHEVAR'};$as_echo "$as_val"'`" = xyes; then :
+  if ${CFLAGS+:} false; then :
+  case " $CFLAGS " in
+    *" $flag "*)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS already contains \$flag"; } >&5
+  (: CFLAGS already contains $flag) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      ;;
+    *)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS=\"\$CFLAGS \$flag\""; } >&5
+  (: CFLAGS="$CFLAGS $flag") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      CFLAGS="$CFLAGS $flag"
+      ;;
+   esac
+else
+  CFLAGS="$flag"
+fi
+
+else
+  :
+fi
+
+done
+
+
+
+for flag in -Wwrite-strings; do
+  as_CACHEVAR=`$as_echo "ax_cv_check_cflags__$flag" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts $flag" >&5
+$as_echo_n "checking whether C compiler accepts $flag... " >&6; }
+if eval \${$as_CACHEVAR+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  $flag"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  eval "$as_CACHEVAR=yes"
+else
+  eval "$as_CACHEVAR=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+eval ac_res=\$$as_CACHEVAR
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+if test x"`eval 'as_val=${'$as_CACHEVAR'};$as_echo "$as_val"'`" = xyes; then :
+  if ${CFLAGS+:} false; then :
+  case " $CFLAGS " in
+    *" $flag "*)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS already contains \$flag"; } >&5
+  (: CFLAGS already contains $flag) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      ;;
+    *)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS=\"\$CFLAGS \$flag\""; } >&5
+  (: CFLAGS="$CFLAGS $flag") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      CFLAGS="$CFLAGS $flag"
+      ;;
+   esac
+else
+  CFLAGS="$flag"
+fi
+
+else
+  :
+fi
+
+done
+
+
+
+for flag in -Wundef; do
+  as_CACHEVAR=`$as_echo "ax_cv_check_cflags__$flag" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts $flag" >&5
+$as_echo_n "checking whether C compiler accepts $flag... " >&6; }
+if eval \${$as_CACHEVAR+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  $flag"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  eval "$as_CACHEVAR=yes"
+else
+  eval "$as_CACHEVAR=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+eval ac_res=\$$as_CACHEVAR
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+if test x"`eval 'as_val=${'$as_CACHEVAR'};$as_echo "$as_val"'`" = xyes; then :
+  if ${CFLAGS+:} false; then :
+  case " $CFLAGS " in
+    *" $flag "*)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS already contains \$flag"; } >&5
+  (: CFLAGS already contains $flag) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      ;;
+    *)
+      { { $as_echo "$as_me:${as_lineno-$LINENO}: : CFLAGS=\"\$CFLAGS \$flag\""; } >&5
+  (: CFLAGS="$CFLAGS $flag") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+      CFLAGS="$CFLAGS $flag"
+      ;;
+   esac
+else
+  CFLAGS="$flag"
+fi
+
+else
+  :
+fi
+
+done
+
   fi
 
 
diff --git a/doc/Makefile.in b/doc/Makefile.in
index 5d1b4e4..0e19726 100644
--- a/doc/Makefile.in
+++ b/doc/Makefile.in
@@ -83,6 +83,9 @@ DIST_COMMON = $(srcdir)/Makefile.in $(srcdir)/Makefile.am \
 	$(dist_sysconf_DATA)
 ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
 am__aclocal_m4_deps = $(top_srcdir)/m4/argz.m4 \
+	$(top_srcdir)/m4/ax_append_compile_flags.m4 \
+	$(top_srcdir)/m4/ax_append_flag.m4 \
+	$(top_srcdir)/m4/ax_check_compile_flag.m4 \
 	$(top_srcdir)/m4/ax_check_openssl.m4 \
 	$(top_srcdir)/m4/gcc_stack_protect.m4 \
 	$(top_srcdir)/m4/libtool.m4 $(top_srcdir)/m4/ltdl.m4 \
diff --git a/help/Makefile.in b/help/Makefile.in
index a8cc36e..a06ca4b 100644
--- a/help/Makefile.in
+++ b/help/Makefile.in
@@ -83,6 +83,9 @@ DIST_COMMON = $(srcdir)/Makefile.in $(srcdir)/Makefile.am \
 	$(dist_helpf_DATA)
 ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
 am__aclocal_m4_deps = $(top_srcdir)/m4/argz.m4 \
+	$(top_srcdir)/m4/ax_append_compile_flags.m4 \
+	$(top_srcdir)/m4/ax_append_flag.m4 \
+	$(top_srcdir)/m4/ax_check_compile_flag.m4 \
 	$(top_srcdir)/m4/ax_check_openssl.m4 \
 	$(top_srcdir)/m4/gcc_stack_protect.m4 \
 	$(top_srcdir)/m4/libtool.m4 $(top_srcdir)/m4/ltdl.m4 \
diff --git a/libltdl/Makefile.in b/libltdl/Makefile.in
index 1778e81..bcab3b4 100644
--- a/libltdl/Makefile.in
+++ b/libltdl/Makefile.in
@@ -90,6 +90,9 @@ DIST_COMMON = $(srcdir)/Makefile.in $(srcdir)/Makefile.am \
 	$(am__ltdlinclude_HEADERS_DIST) COPYING.LIB README
 ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
 am__aclocal_m4_deps = $(top_srcdir)/m4/argz.m4 \
+	$(top_srcdir)/m4/ax_append_compile_flags.m4 \
+	$(top_srcdir)/m4/ax_append_flag.m4 \
+	$(top_srcdir)/m4/ax_check_compile_flag.m4 \
 	$(top_srcdir)/m4/ax_check_openssl.m4 \
 	$(top_srcdir)/m4/gcc_stack_protect.m4 \
 	$(top_srcdir)/m4/libtool.m4 $(top_srcdir)/m4/ltdl.m4 \
diff --git a/m4/ax_append_compile_flags.m4 b/m4/ax_append_compile_flags.m4
new file mode 100644
index 0000000..1f8e708
--- /dev/null
+++ b/m4/ax_append_compile_flags.m4
@@ -0,0 +1,65 @@
+# ===========================================================================
+#  http://www.gnu.org/software/autoconf-archive/ax_append_compile_flags.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_APPEND_COMPILE_FLAGS([FLAG1 FLAG2 ...], [FLAGS-VARIABLE], [EXTRA-FLAGS])
+#
+# DESCRIPTION
+#
+#   For every FLAG1, FLAG2 it is checked whether the compiler works with the
+#   flag.  If it does, the flag is added FLAGS-VARIABLE
+#
+#   If FLAGS-VARIABLE is not specified, the current language's flags (e.g.
+#   CFLAGS) is used.  During the check the flag is always added to the
+#   current language's flags.
+#
+#   If EXTRA-FLAGS is defined, it is added to the current language's default
+#   flags (e.g. CFLAGS) when the check is done.  The check is thus made with
+#   the flags: "CFLAGS EXTRA-FLAGS FLAG".  This can for example be used to
+#   force the compiler to issue an error when a bad flag is given.
+#
+#   NOTE: This macro depends on the AX_APPEND_FLAG and
+#   AX_CHECK_COMPILE_FLAG. Please keep this macro in sync with
+#   AX_APPEND_LINK_FLAGS.
+#
+# LICENSE
+#
+#   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
+#
+#   This program is free software: you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation, either version 3 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+#serial 3
+
+AC_DEFUN([AX_APPEND_COMPILE_FLAGS],
+[AC_REQUIRE([AX_CHECK_COMPILE_FLAG])
+AC_REQUIRE([AX_APPEND_FLAG])
+for flag in $1; do
+  AX_CHECK_COMPILE_FLAG([$flag], [AX_APPEND_FLAG([$flag], [$2])], [], [$3])
+done
+])dnl AX_APPEND_COMPILE_FLAGS
diff --git a/m4/ax_append_flag.m4 b/m4/ax_append_flag.m4
new file mode 100644
index 0000000..1d38b76
--- /dev/null
+++ b/m4/ax_append_flag.m4
@@ -0,0 +1,69 @@
+# ===========================================================================
+#      http://www.gnu.org/software/autoconf-archive/ax_append_flag.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_APPEND_FLAG(FLAG, [FLAGS-VARIABLE])
+#
+# DESCRIPTION
+#
+#   FLAG is appended to the FLAGS-VARIABLE shell variable, with a space
+#   added in between.
+#
+#   If FLAGS-VARIABLE is not specified, the current language's flags (e.g.
+#   CFLAGS) is used.  FLAGS-VARIABLE is not changed if it already contains
+#   FLAG.  If FLAGS-VARIABLE is unset in the shell, it is set to exactly
+#   FLAG.
+#
+#   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
+#   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
+#
+#   This program is free software: you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation, either version 3 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+#serial 2
+
+AC_DEFUN([AX_APPEND_FLAG],
+[AC_PREREQ(2.59)dnl for _AC_LANG_PREFIX
+AS_VAR_PUSHDEF([FLAGS], [m4_default($2,_AC_LANG_PREFIX[FLAGS])])dnl
+AS_VAR_SET_IF(FLAGS,
+  [case " AS_VAR_GET(FLAGS) " in
+    *" $1 "*)
+      AC_RUN_LOG([: FLAGS already contains $1])
+      ;;
+    *)
+      AC_RUN_LOG([: FLAGS="$FLAGS $1"])
+      AS_VAR_SET(FLAGS, ["AS_VAR_GET(FLAGS) $1"])
+      ;;
+   esac],
+  [AS_VAR_SET(FLAGS,["$1"])])
+AS_VAR_POPDEF([FLAGS])dnl
+])dnl AX_APPEND_FLAG
diff --git a/m4/ax_check_compile_flag.m4 b/m4/ax_check_compile_flag.m4
new file mode 100644
index 0000000..c3a8d69
--- /dev/null
+++ b/m4/ax_check_compile_flag.m4
@@ -0,0 +1,72 @@
+# ===========================================================================
+#   http://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS])
+#
+# DESCRIPTION
+#
+#   Check whether the given FLAG works with the current language's compiler
+#   or gives an error.  (Warnings, however, are ignored)
+#
+#   ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
+#   success/failure.
+#
+#   If EXTRA-FLAGS is defined, it is added to the current language's default
+#   flags (e.g. CFLAGS) when the check is done.  The check is thus made with
+#   the flags: "CFLAGS EXTRA-FLAGS FLAG".  This can for example be used to
+#   force the compiler to issue an error when a bad flag is given.
+#
+#   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
+#   macro in sync with AX_CHECK_{PREPROC,LINK}_FLAG.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
+#   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
+#
+#   This program is free software: you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation, either version 3 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+#serial 2
+
+AC_DEFUN([AX_CHECK_COMPILE_FLAG],
+[AC_PREREQ(2.59)dnl for _AC_LANG_PREFIX
+AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl
+AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [
+  ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS
+  _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1"
+  AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
+    [AS_VAR_SET(CACHEVAR,[yes])],
+    [AS_VAR_SET(CACHEVAR,[no])])
+  _AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags])
+AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes],
+  [m4_default([$2], :)],
+  [m4_default([$3], :)])
+AS_VAR_POPDEF([CACHEVAR])dnl
+])dnl AX_CHECK_COMPILE_FLAGS
diff --git a/modules/Makefile.in b/modules/Makefile.in
index bab911c..b4dda2e 100644
--- a/modules/Makefile.in
+++ b/modules/Makefile.in
@@ -83,6 +83,9 @@ DIST_COMMON = $(srcdir)/Makefile.in $(srcdir)/Makefile.am \
 	$(top_srcdir)/depcomp
 ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
 am__aclocal_m4_deps = $(top_srcdir)/m4/argz.m4 \
+	$(top_srcdir)/m4/ax_append_compile_flags.m4 \
+	$(top_srcdir)/m4/ax_append_flag.m4 \
+	$(top_srcdir)/m4/ax_check_compile_flag.m4 \
 	$(top_srcdir)/m4/ax_check_openssl.m4 \
 	$(top_srcdir)/m4/gcc_stack_protect.m4 \
 	$(top_srcdir)/m4/libtool.m4 $(top_srcdir)/m4/ltdl.m4 \
diff --git a/modules/core/Makefile.in b/modules/core/Makefile.in
index d9e65f3..cf47b51 100644
--- a/modules/core/Makefile.in
+++ b/modules/core/Makefile.in
@@ -83,6 +83,9 @@ DIST_COMMON = $(srcdir)/Makefile.in $(srcdir)/Makefile.am \
 	$(top_srcdir)/depcomp
 ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
 am__aclocal_m4_deps = $(top_srcdir)/m4/argz.m4 \
+	$(top_srcdir)/m4/ax_append_compile_flags.m4 \
+	$(top_srcdir)/m4/ax_append_flag.m4 \
+	$(top_srcdir)/m4/ax_check_compile_flag.m4 \
 	$(top_srcdir)/m4/ax_check_openssl.m4 \
 	$(top_srcdir)/m4/gcc_stack_protect.m4 \
 	$(top_srcdir)/m4/libtool.m4 $(top_srcdir)/m4/ltdl.m4 \
diff --git a/src/Makefile.in b/src/Makefile.in
index 174ac67..aa14618 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -85,6 +85,9 @@ DIST_COMMON = $(srcdir)/Makefile.in $(srcdir)/Makefile.am \
 	$(top_srcdir)/ylwrap
 ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
 am__aclocal_m4_deps = $(top_srcdir)/m4/argz.m4 \
+	$(top_srcdir)/m4/ax_append_compile_flags.m4 \
+	$(top_srcdir)/m4/ax_append_flag.m4 \
+	$(top_srcdir)/m4/ax_check_compile_flag.m4 \
 	$(top_srcdir)/m4/ax_check_openssl.m4 \
 	$(top_srcdir)/m4/gcc_stack_protect.m4 \
 	$(top_srcdir)/m4/libtool.m4 $(top_srcdir)/m4/ltdl.m4 \
diff --git a/tools/Makefile.in b/tools/Makefile.in
index 7b743e1..5d2a4cb 100644
--- a/tools/Makefile.in
+++ b/tools/Makefile.in
@@ -85,6 +85,9 @@ DIST_COMMON = $(srcdir)/Makefile.in $(srcdir)/Makefile.am \
 	$(top_srcdir)/depcomp README
 ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
 am__aclocal_m4_deps = $(top_srcdir)/m4/argz.m4 \
+	$(top_srcdir)/m4/ax_append_compile_flags.m4 \
+	$(top_srcdir)/m4/ax_append_flag.m4 \
+	$(top_srcdir)/m4/ax_check_compile_flag.m4 \
 	$(top_srcdir)/m4/ax_check_openssl.m4 \
 	$(top_srcdir)/m4/gcc_stack_protect.m4 \
 	$(top_srcdir)/m4/libtool.m4 $(top_srcdir)/m4/ltdl.m4 \