[omxplayer] Don't sync up to passthrough audio packets - let GPU handle it

This code was just broken.
When sync is lost it attempts to identify how many bytes to skip to regain sync,
but does nothing with that skip count - just drops the whole frame.

It also stops EAC3 from being passed through.

The GPU has similar sync detection code which does avoid dropping the whole frame,
so just pass the packets through and let GPU deal with it.
ffmpeg: Bump to n2.4.3
Fix for channel count when using request_channel_layout with TrueHD
Exit when seeking beyond end of file

See: https://github.com/popcornmix/omxplayer/issues/270
Always enable the timestamp fifo mode and let the GPU choose

See: https://github.com/popcornmix/omxplayer/issues/264
Remove spammy log message from Keyboard
Fix for chapter seeks