new file mode 100644
--- /dev/null
+++ b/m4/stdbool.m4
@@ -0,0 +1,62 @@
+# Check for stdbool.h that conforms to C99.
+
+# Copyright (C) 2002 Free Software Foundation, Inc.
+
+# 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, 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, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+# 02111-1307, USA.
+
+AC_DEFUN([AC_HEADER_STDBOOL],
+  [AC_CACHE_CHECK([for stdbool.h that conforms to C99],
+     [ac_cv_header_stdbool_h],
+     [AC_TRY_COMPILE(
+	[
+	  #include <stdbool.h>
+	  #ifndef bool
+	   "error: bool is not defined"
+	  #endif
+	  #ifndef false
+	   "error: false is not defined"
+	  #endif
+	  #if false
+	   "error: false is not 0"
+	  #endif
+	  #ifndef true
+	   "error: false is not defined"
+	  #endif
+	  #if true != 1
+	   "error: true is not 1"
+	  #endif
+	  #ifndef __bool_true_false_are_defined
+	   "error: __bool_true_false_are_defined is not defined"
+	  #endif
+
+	  struct s { _Bool s: 1; _Bool t; } s;
+
+	  char a[true == 1 ? 1 : -1];
+	  char b[false == 0 ? 1 : -1];
+	  char c[__bool_true_false_are_defined == 1 ? 1 : -1];
+	  char d[(bool) -0.5 == true ? 1 : -1];
+	  bool e = &s;
+	  char f[(_Bool) -0.0 == false ? 1 : -1];
+	  char g[true];
+	  char h[sizeof (_Bool)];
+	  char i[sizeof s.t];
+	],
+	[ return !a + !b + !c + !d + !e + !f + !g + !h + !i; ],
+	[ac_cv_header_stdbool_h=yes],
+	[ac_cv_header_stdbool_h=no])])
+   if test $ac_cv_header_stdbool_h = yes; then
+     AC_DEFINE(HAVE_STDBOOL_H, 1, [Define to 1 if stdbool.h conforms to C99.])
+   fi])