compositor, clients: make damage double-buffered

This change depends on the Wayland commit
"protocol: double-buffered state for wl_surface".

Implement double-buffering of damage in the compositor as required by
the new protocol.

Ensure all Weston demo clients call wl_surface_commit() after
wl_surface_damage().

Mesa does not need a fix for this, as the patch adding
wl_surface_commit() call to Mesa already takes care of damage, too;
Mesa commit: "wayland: use wl_surface_commit()"

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

clients/simple-touch.c

@@ -142,6 +142,10 @@ touch_paint(struct touch *touch, int32_t x, int32_t y, int32_t id)
 	p[2] = c;
 
 	wl_surface_damage(touch->surface, x - 2, y - 2, 5, 5);
+	/* todo: We could queue up more damage before committing, if there
+	 * are more input events to handle.
+	 */
+	wl_surface_commit(touch->surface);
 }
 
 static void

clients/smoke.c

@@ -223,6 +223,7 @@ redraw_handler(struct widget *widget, void *data)
 
 	callback = wl_surface_frame(window_get_wl_surface(smoke->window));
 	wl_callback_add_listener(callback, &listener, smoke);
+	wl_surface_commit(window_get_wl_surface(smoke->window));
 }
 
 static int