Wayland backend: set the opaque region when starting fullscreen

The opaque region is not set when we start the nested
compositor fullscreen. This patch fixes this.

Signed-off-by: Axel Davy <axel.davy@ens.fr>

src/compositor-wayland.c

@@ -1613,6 +1613,7 @@ backend_init(struct wl_display *display, int *argc, char *argv[],
 		if (!output)
 			goto err_outputs;
 
+		wayland_output_set_fullscreen(output, 0, 0, NULL);
 		return &c->base;
 	}