[PATCH] configure: fix test-for-synth check with GCC 4.9.0

[Aaro K. <aar...@ik...>]

With GCC 4.9.0 oprofile 0.9.9 build fails on non-PPC platfroms
because the "test-for-synth" configure check result is incorrect:
There is a NULL pointer dereference in the test program, so the compiler
seems to optimize the rest of the code away, and the test will always
succeed regardless whether bfd_elf64_powerpc*_vec are present or not.
Fix by allocating the referred struct statically.

While at it, also include stdio.h to avoid a compiler warning.

Signed-off-by: Aaro Koskinen <aar...@ik...>
---
 m4/binutils.m4 | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/m4/binutils.m4 b/m4/binutils.m4
index 25fb15a..449ce64 100644
--- a/m4/binutils.m4
+++ b/m4/binutils.m4
@@ -27,8 +27,10 @@ if test "$OS" = "Linux"; then
 	AC_MSG_CHECKING([whether bfd_get_synthetic_symtab() exists in BFD library])
 	rm -f test-for-synth
 	AC_LANG_CONFTEST(
-		[AC_LANG_PROGRAM([[#include <bfd.h>]],
-			[[asymbol * synthsyms;	bfd * ibfd = 0; 
+		[AC_LANG_PROGRAM([[#include <bfd.h>]
+				  [#include <stdio.h>]
+				  [static bfd _ibfd;]],
+			[[asymbol * synthsyms;	bfd * ibfd = &_ibfd;
 			long synth_count = bfd_get_synthetic_symtab(ibfd, 0, 0, 0, 0, &synthsyms);
 			extern const bfd_target bfd_elf64_powerpc_vec;
 			extern const bfd_target bfd_elf64_powerpcle_vec;
-- 
1.9.0