stagefright: Move to 64 available tracks

Many games use numerous tracks.  If the system
runs out of tracks, new tracks won't be able
to be created.  This has been causing notifications
not to play if many apps are holding open tracks.

Issue: BACON-6

Change-Id: I9cea51b9bd678feba31a88e17dd22083b01d81de
stagefright: stop audio source if player fails to start

Change-Id: I70083f8bfe8409283e52eea017d27d94767c5244