It allows VLD VC-1/WMV3 decoding using DXVA2 (GPU assisted decoding API under
VISTA and Windows 7).
 It is implemented by using AVHWAccel API.


git-svn-id: file:///var/local/repositories/ffmpeg/trunk@21424 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b