lilypond devel 2.19.12

Closes #31875.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
mesos: only builds on Mountain Lion.

Using GCC 4.9, LLVM GCC and Clang all fail.
mesos: add 0.19.1 bottle.

Closes #31259.
Closes #31884.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
mpd & mpdscribble: fix plist
mpd: update 0.18.12 bottle.
mpdscribble: update 0.22 bottle.