E.g. chromaprint expects to be fed 16bit signed PCM
in native endianness, yet there was no check for this.
Similarly for other muxers. Use the new
FF_OFMT_FLAG_ONLY_DEFAULT_CODECS to enfore this where
appropriate, e.g. for pcm/raw muxers.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>