Enable use of FFMPEG codecs for extended formats

Fix the build for ffmpeg decoding.
Adapted from:
Taichi Nishimura: http://review.cyanogenmod.org/#/c/63496/
Hashcode: http://review.cyanogenmod.org/#/c/63517/

Change-Id: Ia99f117fad1e9d4e1889febd55b7d14772decc8e
domx: modify native for stagefright-plugins

Fix the build for ffmpeg decoding.
Adapted from:
Taichi Nishimura: http://review.cyanogenmod.org/#/c/63496/
Hashcode: http://review.cyanogenmod.org/#/c/63516/

Change-Id: I1915a99810d66561697e29f5e8c52afd6663182f