Fix nonnull detection on older GCC.
Fix nonnull detection on older GCC.

DELTA=6  (4 added, 0 deleted, 2 changed)

git-svn-id: 741c308154f1e22deafec9707230e8b816ec4ca6@603 7dc7ac4e-7543-0410-b95c-c1676fc8e2a3

chao787/GTM-mirror,chao787/GTM-mirror,chao787/GTM-mirror