Fix AudioTrack retrograde getPosition when restoring tracks

mReleased represents the number of frames written to the
track, but was cleared on start() causing a mismatch if the
client wrote to the track before starting.  Moved the clearing
to entering the STATE_STOPPED or STATE_FLUSHED state.

Bug: 18017947
Bug: 18022276
Change-Id: I3788c98c4c3c4d9cc004378432797b3f3138e22e
1 file changed