stagefright: Add support for high frame rate video recording

HFR is a slow-motion recording feature where framerate
is increased at capture, but file is composed to play
back at normal rate, giving a net result of slow-motion.

Include timeless HFR fixes:
  Correct total duration of HFR clips
  Avoid multiplying video duration by HFR ratio
  HSR: Check if HSR enabled, use HFR value for HSR
  HSR: Read framerate from HSR key
  Correct timescale in MvHd for HFR
  Remove target specific checks for HFR

Change-Id: Ic54495f9efc9afb5e0a262d993308a40491f1035