AI 143785: am: CL 143775 am: CL 143620 Attempt for fixing crash in...

AI 143785: am: CL 143775 am: CL 143620 Attempt for fixing crash in AudioFlinger::MixerThread::dumpTracks() seen in bug report for issue 1747119.
  AudioFlinger::MixerThread::dumpTracks() was reading mTracks[] vector instead of mActiveTracks[] when dumping active tracks.
  Original author: elaurent
  Merged from: //branches/cupcake/...
  Original author: android-build
  Merged from: //branches/donutburger/...

Automated import of CL 143785