simple-damage: fix rotating-transform option

If --rotating-transform is set, the damage calculation of the previous position of the ball has to be done with the old transform value, not the already updated one.

Note: this is still broken when using in combination with surface damage and viewport, as it's a rather complicated scenario and surface-damage is kinda legacy anyways.

This helps a lot on weston but there seem to be some some issues left in the compositor. On mutter with https://gitlab.gnome.org/GNOME/mutter/merge_requests/121 it renders perfectly, with or without --use-damage-buffer.

Helps with: #155

Context: !41 (comment 54445)