compositor: let update_transform deal damage

compositor: let update_transform deal damage

weston_surface_update_transform() is similar to
weston_surface_configure() in that it changes the surface region on
screen. Unlike configure, update_transform forgets to deal damage at
all, yet it is the only place where we can do damage_below() as needed.

Add a damage_below call to deal damage for the old surface region only
when needed. This uses the cached state from surface->transform to get
the old region.

Add a damage call to deal damage for the new surface region, after
updating the cached state.

Add a repaint call, since we have changed the scene and should render it
out.

This change fixes the rotation not updating the screen properly.

Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>