ffmpeg: update to 2.3.1

Changes:
Disable SIMD usage; creates build errors
Disable runtime cpudetect as it's all disabled
Re-enable compiler optimizations
re-enable stripping

Signed-off-by: Ian Leonard <antonlacon@gmail.com>
ffmpeg: Have the custom Vorbis decoder support select the Ogg demuxer.

Signed-off-by: Ian Leonard <antonlacon@gmail.com>
ffmpeg: Drop the libdlna profile from the Custom ffmpeg option. Libdlna is no longer in the package feed, and has an inactive
upstream.

Signed-off-by: Ian Leonard <antonlacon@gmail.com>
ffmpeg: add audio-dec profile to libffmpeg-custom

Signed-off-by: Ian Leonard <antonlacon@gmail.com>
ffmpeg: add external libraries section to Config.in

Signed-off-by: Ian Leonard <antonlacon@gmail.com>
ffmpeg: improve minidlna profile

Minidlna has no need to mux streams, or be able to read network streams at this point in time, so remove this support from
libffmpeg.

Synchronize the minidlna profile between libffmpeg-ucstom and libffmpeg-mini.

Signed-off-by: Ian Leonard <antonlacon@gmail.com>
Merge pull request #195 from antonlacon/ffmpeg-2.3.x

ffmpeg: Update to 2.3.1 and other cleanup