xwayland: Add version command line option

Xorg supports the '-version' command line option, add something similar
to Xwayland.

Closes: xorg/xserver#976
Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>
Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
4 jobs for xwayland-version in 4 minutes and 23 seconds (queued for 1 second)
Status Job ID Name Coverage
  Docker Image
passed #1634584
debian-testing

00:00:30

 
  Build And Test
passed #1634585
autotools

00:03:53

passed #1634586
meson

00:02:07

passed #1634587
meson-noglamor

00:00:36