Fixes bug #573595.
Unref incoming buffers when we're done. Reindent, clean up white space. Fix comments.
Original commit message from CVS: * configure.ac: * sys/Makefile.am: Add new directory for new acmmp3dec plugin * sys/acmenc/Makefile.am: * sys/acmenc/acmmp3dec.c: Add new acmmp3dec plugin, which uses ACM for decoding mp3 on windows.