clutter: Avoid rounding compensation when invalidating 2D actors

clutter: Avoid rounding compensation when invalidating 2D actors

This allows the redraw clip to be more constrained, so MetaCullable doesn't
end up rendering portions of window shadows, frame and background when a
window invalidates (part of) its contents.

https://bugzilla.gnome.org/show_bug.cgi?id=782344

Origin: https://gitlab.gnome.org/GNOME/mutter/commit/a7df459416d
Bug-Ubuntu: https://launchpad.net/bugs/1767648
Bug-GNOME: https://bugzilla.gnome.org/show_bug.cgi?id=782344
Applied-Upstream: 3.30.3

Gbp-Pq: Name clutter-Avoid-rounding-compensation-when-invalidating-2D-.patch