[mutter] clutter-backend: Default to scale 1

[Robert Mader <rmader src gnome org>]

commit dbff32ec5c14171d62cdd58bb8f48c7ddff36420
Author: Daniel van Vugt <daniel van vugt canonical com>
Date:   Fri Jul 3 18:05:51 2020 +0800

    clutter-backend: Default to scale 1
    
    So we at least don't trigger assertions for invalid scales of zero.
    
    Closes: https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/2957
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1349

 clutter/clutter/clutter-backend.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/clutter/clutter/clutter-backend.c b/clutter/clutter/clutter-backend.c
index 20d8961154..bb3c0f6ca5 100644
--- a/clutter/clutter/clutter-backend.c
+++ b/clutter/clutter/clutter-backend.c
@@ -601,6 +601,8 @@ clutter_backend_init (ClutterBackend *self)
   self->units_serial = 1;
 
   self->dummy_onscreen = NULL;
+
+  self->fallback_resource_scale = 1.f;
 }
 
 void