Bug 3438258 Add SurfaceTexture as MediaPlayer sink

This change enables the use of a SurfaceTexture in place of a Surface
as the video sink for an android.media.MediaPlayer. The new API
MediaPlayer.setTexture is currently hidden.

This includes:
 - New Java and C++ interfaces
 - C++ plumbing and implementation (JNI, Binder)
 - Stagefright AwesomePlayer and NuPlayer use ANativeWindow
   (either Surface or SurfaceTextureClient)

Change-Id: I2b568bee143d9eaf3dfc6cc4533c1bebbd5afc51