I looks like some --enable/ flags have been cleaned up. IPv6 support was added, afaik. I'll take a look at it later.
Created attachment 251909 [details, diff] ebuild patch
Created attachment 251911 [details, diff] updated mpd.conf patch
Why -disable-wavpack ?
Created attachment 251915 [details] updated mpd.conf patch pid_file must not be set in init.d / start-stop-daemon mode
mpd-0.16_alpha4 has been released.
mpd-1.16 is in tree now, thanks hwoarang!