Carlos Garnacho authored Dec 10, 2018 and Jonas Ådahl committed May 24, 2019

It is now separated into meta_xwayland_start(), which picks an unused
display and sets up the sockets, and meta_xwayland_init_xserver(), which
does the actual exec of Xwayland and MetaX11Display initialization.

This differentiation will be useful when Mutter is able to launch Xwayland
lazily, currently the former calls into the latter.

!420