avcodec: Remove libstagefright

It serves absolutely no purpose other than to confuse potentional
Android developers about how to use hardware acceleration properly
on the the platform. The stagefright "API" is not public, and the
MediaCodec API is the proper way to do this.

Furthermore, stagefright support in avcodec needs a series of
magic incantations and version-specific stuff, such that
using it actually provides downsides compared just using the actual
Android frameworks properly, in that it is a lot more work and confusion
to get it even running. It also leads to a lot of misinformation, like
these sorts of comments (in [1]) that are absolutely incorrect.

[1] http://stackoverflow.com/a/29362353/3115956

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

libavcodec/allcodecs.c

@@ -572,7 +572,6 @@ void avcodec_register_all(void)
     REGISTER_ENCDEC (LIBSCHROEDINGER,   libschroedinger);
     REGISTER_ENCODER(LIBSHINE,          libshine);
     REGISTER_ENCDEC (LIBSPEEX,          libspeex);
-    REGISTER_DECODER(LIBSTAGEFRIGHT_H264, libstagefright_h264);
     REGISTER_ENCODER(LIBTHEORA,         libtheora);
     REGISTER_ENCODER(LIBTWOLAME,        libtwolame);
     REGISTER_ENCDEC (LIBUTVIDEO,        libutvideo);