--- /dev/null
+# ===========================================================================
+# http://www.gnu.org/software/autoconf-archive/ax_check_flag.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+# AX_CHECK_PREPROC_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS])
+# AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS])
+# AX_CHECK_LINK_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS])
+# AX_APPEND_FLAG(FLAG, [FLAGS-VARIABLE])
+# AX_APPEND_COMPILE_FLAGS([FLAG1 FLAG2 ...], [FLAGS-VARIABLE], [EXTRA-FLAGS])
+# AX_APPEND_LINK_FLAGS([FLAG1 FLAG2 ...], [FLAGS-VARIABLE], [EXTRA-FLAGS])
+#
+# DESCRIPTION
+#
+# Check whether the given FLAG works with the current language's
+# preprocessor/compiler/linker, or whether they give 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 us thus made
+# with the following flags: "CFLAGS EXTRA-FLAGS FLAG". EXTRA-FLAGS can
+# for example be used to force the compiler to issue an error when a bad
+# flag is given.
+#
+# AX_APPEND_FLAG appends the FLAG to the FLAG-VARIABLE shell variable or
+# the current language's flags if not specified. FLAG is not added to
+# FLAG-VARIABLE if it is already in the shell variable.
+#
+# AX_APPEND_COMPILE_FLAGS checks for each FLAG1, FLAG2, etc. using
+# AX_CHECK_COMPILE_FLAG and if the check is successful the flag is added
+# to the appropriate FLAGS variable with AX_APPEND_FLAG. The
+# FLAGS-VARIABLE and EXTRA-FLAGS arguments are the same as in the other
+# macros. AX_APPEND_LINK_FLAGS does the same for linker flags.
+#
+# NOTE: Based on AX_CHECK_COMPILER_FLAGS and AX_CFLAGS_GCC_OPTION.
+#
+# LICENSE
+#
+# Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
+# Copyright (c) 2009 Steven G. Johnson <stevenj@alum.mit.edu>
+# Copyright (c) 2009 Matteo Frigo
+# 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_PREPROC_FLAG],
+[AC_PREREQ(2.59) dnl for _AC_LANG_PREFIX
+AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]cppflags_$4_$1])dnl
+AC_CACHE_CHECK([whether _AC_LANG preprocessor accepts $1], CACHEVAR, [
+ ax_check_save_flags=$CPPFLAGS
+ CPPFLAGS="$CPPFLAGS $4 $1"
+ AC_PREPROC_IFELSE([AC_LANG_PROGRAM()],
+ [AS_VAR_SET([CACHEVAR],[yes])],
+ [AS_VAR_SET([CACHEVAR],[no])])
+ CPPFLAGS=$ax_check_save_flags])
+AS_VAR_IF([CACHEVAR], "yes",
+ [m4_default([$2], :)],
+ [m4_default([$3], :)])
+AS_VAR_POPDEF([CACHEVAR])dnl
+])dnl AX_CHECK_PREPROC_FLAGS
+
+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_VAR_IF([CACHEVAR], "yes",
+ [m4_default([$2], :)],
+ [m4_default([$3], :)])
+AS_VAR_POPDEF([CACHEVAR])dnl
+])dnl AX_CHECK_COMPILE_FLAGS
+
+AC_DEFUN([AX_CHECK_LINK_FLAG],
+[AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_ldflags_$4_$1])dnl
+AC_CACHE_CHECK([whether the linker accepts $1], CACHEVAR, [
+ ax_check_save_flags=$LDFLAGS
+ LDFLAGS="$LDFLAGS $4 $1"
+ AC_LINK_IFELSE([AC_LANG_PROGRAM()],
+ [AS_VAR_SET([CACHEVAR],[yes])],
+ [AS_VAR_SET([CACHEVAR],[no])])
+ LDFLAGS=$ax_check_save_flags])
+AS_VAR_IF([CACHEVAR], "yes",
+ [m4_default([$2], :)],
+ [m4_default([$3], :)])
+AS_VAR_POPDEF([CACHEVAR])dnl
+])dnl AX_CHECK_LINK_FLAGS
+
+
+AC_DEFUN([AX_APPEND_FLAG],
+[AC_PREREQ(2.59) dnl for _AC_LANG_PREFIX
+AC_REQUIRE([AC_PROG_GREP])
+AS_VAR_PUSHDEF([FLAGS], [m4_default($2,_AC_LANG_PREFIX[]FLAGS)])dnl
+AS_VAR_SET_IF([FLAGS],
+ [AS_IF([AS_ECHO(" $[]FLAGS ") | $GREP " $1 " 2>&1 >/dev/null],
+ [AC_RUN_LOG([: FLAGS already contains $1])],
+ [AC_RUN_LOG([: FLAGS="$FLAGS $1"])
+ AS_VAR_APPEND([FLAGS], [" $1"])])],
+ [AS_VAR_SET([FLAGS],[$1])])
+AS_VAR_POPDEF([FLAGS])dnl
+])dnl AX_APPEND_FLAG
+
+AC_DEFUN([AX_APPEND_COMPILE_FLAGS],
+[for flag in $1; do
+ AX_CHECK_COMPILE_FLAG([$flag], [AX_APPEND_FLAG([$flag], [$2])], [], [$3])
+done
+])dnl AX_APPEND_COMPILE_FLAGS
+
+AC_DEFUN([AX_APPEND_LINK_FLAGS],
+[for flag in $1; do
+ AX_CHECK_LINK_FLAG([$flag], [AX_APPEND_FLAG([$flag], [m4_default([$2], [LDFLAGS])])], [], [$3])
+done
+])dnl AX_APPEND_LINK_FLAGS