wayland: Use scale from core wl_output protocol

The “xdg-output” protocol provides clients with the outputs size and
position in compositor coordinates, and does not provide the output
scale which is already provided by the core “wl_output” protocol.

So when receiving the wl_output scale event, we should update the scale
regardless of “xdg-output” support, otherwise the scale will remain to
its default value of 1 and the surface will be scaled up by the
compositor to match the actual output scale, which causes blurry fonts
and widgets.

Fixes: GNOME/gtk#1901
Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
4 jobs for issue1901-gtk3 in 19 minutes and 17 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #305729
fedora-autotools

00:11:23

passed #305730
fedora-meson

00:08:42

manual #305732
win32 allowed to fail manual
msys2-mingw32-autotools
passed #305731
win32
msys2-mingw32-meson

00:14:15