[Sheepdog] [PATCH] fix autoconf warnings

[Christoph Hellwig]

It seems like newer autoconf versions need code that is test compiled
to be enclosed by a AC_LANG_SOURCE macro.

Signed-off-by: Christoph Hellwig <hch at lst.de>

Index: sheepdog/configure.ac
===================================================================
--- sheepdog.orig/configure.ac	2012-05-10 16:34:09.183990201 +0200
+++ sheepdog/configure.ac	2012-05-10 16:34:13.471990160 +0200
@@ -142,7 +142,7 @@ AC_CONFIG_FILES([Makefile
 cc_supports_flag() {
 	local CFLAGS="$@"
 	AC_MSG_CHECKING([whether $CC supports "$@"])
-	AC_COMPILE_IFELSE([int main(){return 0;}] ,
+	AC_COMPILE_IFELSE([AC_LANG_SOURCE([int main(){return 0;}])] ,
 			  [RC=0; AC_MSG_RESULT([yes])],
 			  [RC=1; AC_MSG_RESULT([no])])
 	return $RC