Use AC_LANG_SOURCE to fix autoconf warnings.

ChangeLog

@@ -1,3 +1,8 @@
+2012-06-22  Carlos O'Donell  <carlos_odonell@mentor.com>
+
+	* configure.in: Use AC_LANG_SOURCE.
+	* configure: Regenerate.
+
 2012-06-22  Roland McGrath  <roland@hack.frob.com>
 
 	* configure.in (libc_cv_localstatedir): New substituted variable.

configure.in

@@ -278,12 +278,12 @@ if test "x$systemtap" != xno; then
   AC_CACHE_CHECK([for systemtap static probe support], libc_cv_sdt, [dnl
   old_CFLAGS="$CFLAGS"
   CFLAGS="-std=gnu99 $CFLAGS"
-  AC_COMPILE_IFELSE([#include <sys/sdt.h>
+  AC_COMPILE_IFELSE([AC_LANG_SOURCE([[#include <sys/sdt.h>
 void foo (int i, void *p)
 {
   asm ("" STAP_PROBE_ASM (foo, bar, STAP_PROBE_ASM_TEMPLATE (2)) ""
        :: STAP_PROBE_ASM_OPERANDS (2, i, p));
-}], [libc_cv_sdt=yes], [libc_cv_sdt=no])
+}]])], [libc_cv_sdt=yes], [libc_cv_sdt=no])
   CFLAGS="$old_CFLAGS"])
   if test $libc_cv_sdt = yes; then
     AC_DEFINE([USE_STAP_PROBE])