Improved three opengl autoconf macros

Main features added:
- Support action-if-found and not-found hook
- Export HAVE_GL, HAVE_GLU, and HAVE_GLUT preprocessor symbol
- Add necessary flags to CFLAGS/LIBS by default, but can be disabled by
  overwritting action-if-found hook.
- Fail the configure script if lib not found. This feature can be disabled by
  overwritting action-if-not-found hook
- Fix problems on Mac OSX. Been tested on Linux (Ubuntu) and OSX
- Use --with-xquartz-gl instead of --with-gl=x for using X11 on OSX

Two new macros added:
- ax_save_flags_with_prefix.m4: save flags and pushes flag with prefix to the
  flag.
  AX_SAVE_FLAGS_WITH_PREFIX([GL],[[CFLAGS],[LIBS]]) would expands to
    gl_saved_flag_cflags="$CFLAGS"
    gl_saved_flag_libs="$LIBS"
    CFLAGS="$GL_CFLAGS $CFLAGS"
    LIBS="$GL_LIBS $LIBS"
- ax_restore_flags_with_prefix.m4: restore the flags.

1 files changed, 66 insertions, 0 deletions

diff --git a/m4/ax_restore_flags_with_prefix.m4 b/m4/ax_restore_flags_with_prefix.m4
new file mode 100644
index 0000000..9803210
--- /dev/null
+++ b/m4/ax_restore_flags_with_prefix.m4
@@ -0,0 +1,66 @@
+# ================================================================================
+#  http://www.gnu.org/software/autoconf-archive/ax_restore_flags_with_prefix.html
+# ================================================================================
+#
+# SYNOPSIS
+#
+#   AX_RESTORE_FLAGS_WITH_PREFIX(PREFIX, LIST-OF-FLAGS)
+#
+# DESCRIPTION
+#
+#   Restore the flags saved by AX_SAVE_FLAGS_WITH_PREFIX.
+#
+#   Expansion example: AX_RESTORE_FLAGS_WITH_PREFIX([GL], [[CFLAGS],[LIBS]])
+#   expands to
+#
+#     CFLAGS="$gl_saved_flag_cflags"
+#     LIBS="$gl_saved_flag_libs"
+#
+#   One common use case is to define a package specific wrapper macro around
+#   this one, and also restore other variables if needed. For example:
+#
+#     AC_DEFUN([_AX_CHECK_GL_RESTORE_FLAGS], [
+#       AX_RESTORE_FLAGS_WITH_PREFIX([GL],[$1])
+#       AC_LANG_POP([C])
+#     ])
+#
+#     # Restores CFLAGS, LIBS and language state
+#     _AX_CHECK_GL_RESTORE_FLAGS([[CFLAGS],[LIBS]])
+#
+# LICENSE
+#
+#   Copyright (c) 2016 Felix Chern <idryman@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 2 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 1
+
+m4_define([AX_RESTORE_FLAGS_WITH_PREFIX],[
+m4_ifval([$2], [
+m4_car($2)="$_ax_[]m4_tolower($1)_saved_flag_[]m4_tolower(m4_car($2))"
+$0($1, m4_cdr($2))])
+])