simple-egl: Reset opaque region if not fullscreen.

If simple-egl is toggled fullscreen, the opqaue region is set for the surface
but never removed after exiting fullscreen. This patch resets the opaque region
to 0 if the surface is not fullscreen and -o was not passed. This fixes the
problem introduced sometime since d7f282b84e, when this was last fixed.

clients/simple-egl.c

@@ -413,6 +413,8 @@ redraw(void *data, struct wl_callback *callback, uint32_t time)
 			      window->geometry.height);
 		wl_surface_set_opaque_region(window->surface, region);
 		wl_region_destroy(region);
+	} else {
+		wl_surface_set_opaque_region(window->surface, NULL);
 	}
 
 	window->callback = wl_surface_frame(window->surface);