[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.

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.
[dvdplayer] exerimental: don't raise priority of audio thread
handle stereoscopic mode of videos in mixed playlists
remember user selected 3D modes between videos until playback ended
[mmalcodec] Introduce a preroll period to buffer up frames on startup
[omxplayer] Add ability to log more timestamp info in extra debug settings
[omxplayer] Add ability to dump out audio/video data for later debugging
[mmalrenderer] Add choice of 3 deinterlace schemes
[audio] Add settings option to boost centre channel when downmixing

This allows a dB volume increase to be added to centre channel.
This can help improve dialgue in the presence of background music/effects.
It can go up to 30dB for testing purposes, but value of 6 is probably more reasonable.
It is recommended to ensure "Normalise levels on downmix" is enabled when boosting by large values to avoid clipping.

Should work with Pi Sink (dvdplayer/paplayer) and omxplayer
[omxcore] Skip out of flush on error
[SinkPi] Handle multichannel layout more like OMXAudio
[PiSink] Allow audio output latency to be set in settings
[AE] Allow resampler to indicate when it has too much data buffered

The Pi resampler doesn't want more samples submitted when it has a whole input buffer queued,
and drops data in this case. This can be triggered when video clock is enabled and audio is resampled.

The FFMPEG resampler buffers more data internally and wants up to two input buffers submitted.

Add a method to query if there is space for more samples, and return approprate values.
config: Add -finstrument-functions
Revert "config: Add -finstrument-functions"

This reverts commit 13e6b5aab2e86e8c38202147475d5251236b4e51.
Revert "hack: revert squash: don't update originaldts when marked as invalid"

This reverts commit 4085c67b535627e1723ca8d7f82f3cdeaa67f54e.
[omxplayer] Remove unused function
rbp: Use new dispmanx function for vsync callbacks
Revert "rbp: Use new dispmanx function for vsync callbacks"

This reverts commit afbf8fbceaa6649fb4a6bbd9a1cee6087590412b.
[rbp] Default extract thumbnails to false

It can take 80 seconds for a single file on a Pi. It can cause crashes with out-of-memory errors.
It genereates a lot of support issues. Best to default to disabled and let users enable it if they must