xwayland: Damage surface in surface-relative coordinates

In 9141196d

 positional coordinates were added to the damage call of pixmap
flips. The damage box coordinates are in screen space though and we need
to convert them first to surface-relative ones by substracting the origin
of the window.
Signed-off-by: Roman Gilg <subdiff@gmail.com>

hw/xwayland/xwayland-present.c

@@ -497,7 +497,8 @@ xwl_present_flip(WindowPtr present_window,
     xwl_present_reset_timer(xwl_present_window);
 
     xwl_surface_damage(xwl_window->xwl_screen, xwl_window->surface,
-                       damage_box->x1, damage_box->y1,
+                       damage_box->x1 - present_window->drawable.x,
+                       damage_box->y1 - present_window->drawable.y,
                        damage_box->x2 - damage_box->x1,
                        damage_box->y2 - damage_box->y1);