Fix memory leak in h264 decoder. allocated_edge_emu_buffer was being allocated
in both mpegvideo and h264 decoder. Fixed by allowing all (master and duplicate)
contexts to fully initialize in MPV_frame_start and copying these into
H264Contexts.

Mailing list discussion:
[FFmpeg-devel] Memory leak in h264
Tue, 22 Jan 2008 15:22:55

Originally committed as revision 11657 to svn://svn.ffmpeg.org/ffmpeg/trunk
