Backport a crash fix for h.264 from ffmpeg trunk.
Backport a crash fix for h.264 from ffmpeg trunk.

git-svn-id: d0cfa3251018d478e6aaed555a307d7fbba1ac15@771 621663c8-3916-0410-8f58-edc14a8543d5

mrvacbob/perian,mrvacbob/perian,mrvacbob/perian,mrvacbob/perian,mrvacbob/perian