stagefright: Build fixes

 * Fix build without AV_ENHANCEMENTS on

Change-Id: I4bbf3f0a6f5894ddb33b62d99bced2f6247081db
Increase kFastTrackMultiplier from 1 to 2

Change-Id: I158f147295eebcea96e4047d7618069bc48bdd7d
FLAC coded file does not play (single metadata block files)

FLAC files which has the last metadata block flag set in
STREAMINFO were not playing. Sniff of FLAC is modified to
accomodate this set flag.

Change-Id: I76f216cc2cde6e10958324afbc704fc3e5a0e2bf
Author: Gurudatta Bhakte <gurudattax.bhakte@intel.com>
Signed-off-by: Gurudatta Bhakte <gurudattax.bhakte@intel.com>
Signed-off-by: Shuo Gao <shuo.gao@intel.com>
Signed-off-by: Bruce Beare <bruce.j.beare@intel.com>
Signed-off-by: Jack Ren <jack.ren@intel.com>
Author-tracking-BZ: 32421