Fix a crash when VMR-7 (renderless) renderer failed loading.

Refs: #2992.
update ffmpeg (n0.8-19710-g35135a3)
Remove custom code needed in the past in order to successfully link ffmpeg library.
update h264_recov.c for the recent changes
Update our files for the recent FFmpeg changes.
H264 DXVA Decoder: Rewrote h264_dxva.c based on recent h264.c.
h264_dxva.c: update for the recent changes in ffmpeg
MPCVideoDec: Fix compilation.
update CFLAGS and ffmpeg/config.asm and ffmpeg/config.h
Fix DXVA after latest FFmpeg update.
update ffmpeg (n0.8-20097-g9f95e35)
update mpeg12.c
update ffmpeg (n0.8-20207-g710cd0f)