ext/ffmpeg/: Add debugging category everywhere (correctly this time). Don't parse mp3 data (the parser is a piece of ...

Original commit message from CVS:
* ext/ffmpeg/gstffmpeg.c:
* ext/ffmpeg/gstffmpegcodecmap.c:
* ext/ffmpeg/gstffmpegcodecmap.h:
* ext/ffmpeg/gstffmpegcolorspace.c:
* ext/ffmpeg/gstffmpegdec.c: (gst_ffmpegdec_chain):
* ext/ffmpeg/gstffmpegdemux.c:
* ext/ffmpeg/gstffmpegenc.c:
* ext/ffmpeg/gstffmpegmux.c:
* ext/ffmpeg/gstffmpegprotocol.c:
Add debugging category everywhere (correctly this time). Don't
parse mp3 data (the parser is a piece of crap). Fixes #155274
mostly. Seeking pending.