sync: fall back to drop_video_to_sync when hb_avcodec_open() fails, instesd of killing the job.

Patch by John Stebbins. Thanks!



git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@5459 b64f7644-9d1e-0410-96f1-a4d463321fa5