The mpegaudio parser depends on mpegaudiodata.o.

This fixes the following option set:
  --disable-encoders --disable-decoders --disable-parsers --disable-bsfs
  --disable-muxers --disable-demuxers --disable-protocols
  --enable-parser=mpegaudio

Originally committed as revision 9641 to svn://svn.ffmpeg.org/ffmpeg/trunk