m4: update ax_check_compile_flag.m4 from autoconf-archive

I noticed this when doing some M4 macro analysis work, and saw
that the version of `ax_check_compile_flag.m4` in Tor has two serial
lines ('serial 5' and 'serial 6') which is invalid.

We could just fix one of the lines, but it makes more sense to just
sync with upstream, I think.

Import ax_check_compile_flag.m4 from autoconf-archive at latest
commit at time of writing (4e8aab846b0872fba99f1fe02ebcdff178a34c87).

Signed-off-by: Sam James <sam@gentoo.org>

1 files changed, 39 insertions, 37 deletions

diff --git a/m4/ax_check_compile_flag.m4 b/m4/ax_check_compile_flag.m4
index 95df39679e..68fd43d5dd 100644
--- a/m4/ax_check_compile_flag.m4
+++ b/m4/ax_check_compile_flag.m4
@@ -1,43 +1,45 @@
- #   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 <https://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.
- #   Copying and distribution of this file, with or without modification, are
- #   permitted in any medium without royalty provided the copyright notice
- #   and this notice are preserved.  This file is offered as-is, without any
- #   warranty.
+# ===========================================================================
+#  https://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
+#
+# 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.
+#
+#   INPUT gives an alternative input source to AC_COMPILE_IFELSE.
+#
+#   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>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.  This file is offered as-is, without any
+#   warranty.
 
- #serial 5
- #serial 6
+#serial 7
 
- AC_DEFUN([AX_CHECK_COMPILE_FLAG],
- [AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
+AC_DEFUN([AX_CHECK_COMPILE_FLAG],
+[AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
 AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl
-AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [
+AC_CACHE_CHECK([whether the _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([m4_default([$5],[AC_LANG_PROGRAM()])],