libstagefright: Delay release of wakelock in TimedEventQueue

Delay release of wakelock in the TimedEventQueue to
after an event has been processed.
This ensures AP shutdown does not happen while an event
is ready but hasn't been processed yet.

Bug: 11976087.
Change-Id: I9bce83b9ff0f2b4d174a53c95e5b0f135b5ccc70
2 files changed