[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
[cec] Add settings for configuring button repeats