This decoder is build around libxing, a minor modification made to the
Xing mp3 decoder as found in FreeAmp.  I'll be cobbling together a patch
for the Xing codec as it stands in the freeamp CVS to make it into
libxing, though I doubt anyone would be interested, given the I/O model
used in freeamp.  

For some reason, it stopped working at some point in the recent past.  It
outputs garbled sound, more noise than anything.  I'm not sure why it
broke, but I'm not too worried about it, since using this decoder in a
simple pipeline caused major skipping due to the increased CPU usage over
the XAudio decoder...  I'm focusing all my energies on the mpg123 decoder
anyway.
