wayland: start Xwayland on connection to either public X11 socket

Fixes GNOME/mutter#1454
6 jobs for !1508 with xwayland-abstract in 8 minutes and 15 seconds
detached
Status Job ID Name Coverage
  Review
failed #943877
check-commit-log

00:00:20

 
  Build
passed #943878
build-mutter

00:04:52

passed #943880
build-without-native-backend-and-wayland

00:02:33

passed #943879
build-without-opengl-and-glx

00:03:22

 
  Test
passed #943882
can-build-gnome-shell

00:01:50

passed #943881
test-mutter

00:03:23

 
Name Stage Failure
failed
check-commit-log Review

Skipping Git submodules setup
Executing "step_script" stage of the job script
$ ./.gitlab-ci/check-commit-log.sh
From https://gitlab.gnome.org/GNOME/mutter
* branch master -> FETCH_HEAD
Commit 2871b7c2 needs a merge request or issue URL
Cleaning up file based variables
ERROR: Job failed: exit code 1