fix for build error: "#pragma GCC diagnostic not allowed inside functions"

It works in a newest gcc (e.g. 4.6.3) but fails here:
i686-apple-darwin11-llvm-gcc-4.2 (GCC) 4.2.1 (Based on Apple Inc. build
5658) (LLVM build 2336.11.00)

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@55389 954f8c5b-7b00-dc11-b283-0030488c597c