configure: add AC_LANG_SOURCE call within AC_COMPILE_IFELSE

Documentation states that AC_*_IFELSE has to use AC_LANG_SOURCE or
friends in order to generate the source code to compile.
AC_LINK_IFELSE already handles this, thus convert AC_COMPILE_IFELSE
to silence the final autoconf warnings.

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>

diff --git a/configure.ac b/configure.ac
index d2e232b..43e6954 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -111,7 +111,7 @@ AC_DEFUN([LIBDRM_CC_TRY_FLAG], [
   libdrm_save_CFLAGS="$CFLAGS"
   CFLAGS="$CFLAGS $1"
 
-  AC_COMPILE_IFELSE([ ], [libdrm_cc_flag=yes], [libdrm_cc_flag=no])
+  AC_COMPILE_IFELSE([AC_LANG_SOURCE([ ])], [libdrm_cc_flag=yes], [libdrm_cc_flag=no])
   CFLAGS="$libdrm_save_CFLAGS"
 
   if test "x$libdrm_cc_flag" = "xyes"; then