stagefright: Disable AwesomePlayer

Permanently remove StagefrightPlayer codebase & remove its entry
from MediaPlayerFactory as AwesomePlayer is completely replaced
by NuPlayer. Keep the AwesomePlayer codebase to make
libstagefright_timedtext available to NuPlayer via libstagefright.

Conflicts:
	media/libmediaplayerservice/MediaPlayerFactory.cpp

Change-Id: Idfecdc519919ee940817c7bb515433fc37588bd3