Multichannel mp3 in mp4 support ISO/IEC 14496-3:2001/FPDAM 3 (MP3onMP4)

Derived from MPlayer patch by Larry Ruedisueli

Originally committed as revision 3955 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/allcodecs.c

@@ -145,6 +145,7 @@ void avcodec_register_all(void)
     register_avcodec(&mp2_decoder);
     register_avcodec(&mp3_decoder);
     register_avcodec(&mp3adu_decoder);
+    register_avcodec(&mp3on4_decoder);
     register_avcodec(&mace3_decoder);
     register_avcodec(&mace6_decoder);
     register_avcodec(&huffyuv_decoder);