Make Bluetooth audio threads use RT scheduling
Bluetooth threads that are used in audio have deadline
requirements for glitchless playback. Those threads need to be
scheduled as RT tasks to ensure that they can meet the deadline even if
there is high system load.
Bug
37518404
Test: play Bluetooth audio, check for RT with systrace
Merged-In: I4505fbce55e5a4fe18d00dbda23646a60e482efd
Change-Id: I4505fbce55e5a4fe18d00dbda23646a60e482efd
(cherry picked from commit
96c42e70f5c6a74a737739aa9c297cd93540f43e)