wayland: Don't warn if the display is lost, skip exit handlers

wayland: Don't warn if the display is lost, skip exit handlers

There is no need to have every application log a warning when the
Wayland display server goes away, and we are using _exit instead of
exit elsewhere.

This is also what the X11 backend does (see gdk_x_io_error).

https://bugzilla.gnome.org/show_bug.cgi?id=745289