add hacks to work around pulseaudio+xwayland integration deadlocks

add hacks to work around pulseaudio+xwayland integration deadlocks

enlightenment is (I think) the first wayland compositor to run with
in-process pulseaudio integration for audio playback and not just mixer
support. hooray.

this results in a fun issue: if DISPLAY is set, as it must be for x11
clients to function, pulseaudio will unconditionally attempt to use a
blocking socket connection to create a connection to the running xserver.
the only exception here is if x11 support has been compiled out of pulseaudio,
but probably no distro will do that ever.

so, what happens when the compositor thread tries to create a socket connection
to the xserver that the compositor thread has not yet started? absolutely nothing.
forever.

the easiest solution which continues to provide the key press sounds that everyone
loves is to ensure that the pulseaudio connection is created before DISPLAY is ever
set, namely in the xwayland module init.

this will now occur automatically now in the case when the mixer module detects
pulseaudio support.

TL;DR: don't disable mixer module if you use xwayland