frameworks/av: rendering statistics for Stagefright

- this adds extra fps statisticis
- report via dumpsys
 - prints statistics before reset at the end of playback onto
   logcat
 - add resume latency, from play_l to render
 - add seek latency, from seek_l to render
 - enabled using persist.debug.sf.statistics 1

 - print all statistics when seek or resume is issued.

Change-Id: Ia34611b89fbc580481f37c921d862711ffb24434