demux: mp4: more insane rtp cleanup
demux: mp4: more insane rtp cleanup

clueless crap unchecked everywhere,
even demux returning function error codes

xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc