wayland: Compare geometries after chaining up

wayland: Compare geometries after chaining up

After 20176d03, the Wayland backend only synchronizes with the
compositor after a geometry was set, and it was different from
the current geometry.

That commit was mistakenly comparing the geometry before chaining
up, which would yield a false negative on the case where the
client didn't call set_geometry() before commit().

Fix that by caching the old geometry locally, chain up (and thus
apply the new geometry rectangle), then comparing the old and
current geometry rectangles.

(cherry picked from commit cf734999fb9e342811896f70f7c1f415462728a7)

Bug: https://gitlab.gnome.org/GNOME/mutter/issues/150
Origin: upstream, 3.28.3, commit:9d4c7e4e75fc7d03254b2051eb088f216fe36da8

Gbp-Pq: Name wayland-Compare-geometries-after-chaining-up.patch