output-damage: constify wlr_output_damage_add()

include/wlr/types/wlr_output_damage.h

@@ -82,7 +82,7 @@ bool wlr_output_damage_attach_render(struct wlr_output_damage *output_damage,
  * Accumulates damage and schedules a `frame` event.
  */
 void wlr_output_damage_add(struct wlr_output_damage *output_damage,
-	pixman_region32_t *damage);
+	const pixman_region32_t *damage);
 /**
  * Damages the whole output and schedules a `frame` event.
  */

types/wlr_output_damage.c

@@ -168,7 +168,7 @@ bool wlr_output_damage_attach_render(struct wlr_output_damage *output_damage,
 }
 
 void wlr_output_damage_add(struct wlr_output_damage *output_damage,
-		pixman_region32_t *damage) {
+		const pixman_region32_t *damage) {
 	int width, height;
 	wlr_output_transformed_resolution(output_damage->output, &width, &height);