pvr: fix deadlock in TriggerEPGUpdate
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