audio:Avoid AudioTrackThread if Track creation fails

-mAudioTrackThread is starting before the track creation.
 This thread is used to process the audio buffer, which
 is no longer valid if the track creation itself is
 failing.

-Fix is to check for the result of track creation and
 based on the result need to start the mAudioTrackThread.

Change-Id: Ic69e45f4269408ff60fe83390e9f8d0c895582e3
CRs-Fixed: 611668
stagefright: add ClockEstimator API and WindowedLinearFitEstimator

Change-Id: I74474c385848a8eab2ac0da7c069510378e2b217
Smooth out AwesomePlayer

Use clock estimator to smooth out audio time stamps.

Change-Id: Iec1ff30c011069d06ff8051fc4839d00895463d6