[PULL] XQuartz {Add,Remove}EnabledDevice build fixes and other cleanup

[Adam Jackson]

On Sun, 2016-09-11 at 00:03 -0700, Jeremy Huddleston Sequoia wrote:

>       os/connection: Improve abstraction for launchd secure sockets

Mmm, not a huge fan of this one. You're not requiring that $DISPLAY be
an absolute path, so now server startup might fail if there's a file in
cwd named ":0.0". Unlikely I admit but still a dumb reason to fail, and
I can't think of a good reason to want relative paths to work here.

- ajax