Index: automake/cfa.m4
===================================================================
--- automake/cfa.m4	(revision 274da9828f936ece12ef62beeb31fbd780c2fae2)
+++ automake/cfa.m4	(revision fc568163062dc14c2d5de7aa24dfe4d3f53f78fd)
@@ -80,2 +80,19 @@
 	esac
 ])
+
+# http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=blob_plain;f=m4/ax_check_compile_flag.m4
+AC_DEFUN([M4CFA_CHECK_COMPILE_FLAG],
+[AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
+AS_VAR_PUSHDEF([CACHEVAR],[m4cfa_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl
+AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [
+	m4cfa_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS
+	_AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1"
+	AC_COMPILE_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
+		[AS_VAR_SET(CACHEVAR,[yes])],
+		[AS_VAR_SET(CACHEVAR,[no])])
+	_AC_LANG_PREFIX[]FLAGS=$m4cfa_check_save_flags])
+AS_VAR_IF(CACHEVAR,yes,
+	[m4_default([$2], :)],
+	[m4_default([$3], :)])
+AS_VAR_POPDEF([CACHEVAR])dnl
+])dnl M4CFA_CHECK_COMPILE_FLAGS