pvr: fix deadlock in TriggerEPGUpdate
vaapi: lock display when calling vaPutSurface
vaapi: call glFinish before closing context
AppMessenger: support for setting volume
AESinkPUSLSE: Use ApplicationMessenger to alter internal volume
AEStreamInfo: Handle sync headers with extension blocks

Fixes passthrough of Dolby TrueHD audio with Atmos.

Behavior based on FFmpeg patch "mlpdec: support major sync headers with
optional extension blocks" by Hendrik Leppkes.
FFmpeg: Temporarily dolby atmos fixed version
Boost Volume on donwmix (popcornmix cherry-pick