patch ffmpeg avi seek problem

patch ffmpeg avi seek problem
when seeking to a timestamp, ffmpeg seeks to the position in the primary
stream where that timestamp starts. Then seeks to the next interleaved packet
for all other streams. When seeking back to the beginning of the file, this
means the first packet of some streams are missed if those streams start
before the video stream in the file.

git-svn-id: svn://localhost/HandBrake/trunk@3296 b64f7644-9d1e-0410-96f1-a4d463321fa5