There's always the "PCM" decoder plugin, which was never checked by
configure.ac.

MPD can easily be used as a database provider for the proxy database
plugin.  In that case, it needs only one "null" output, and no real
output plugin.

Allow building a smaller MPD binary for people who don't need DSD.

The name "cue" was listed twice in "mpd --version".

EXIT_SUCCESS and EXIT_FAILURE are defined in stdlib.h, not unistd.h.
D'oh!

Move code from the Vorbis and FLAC decoder plugins.

Eliminates the functions _new() and _free().