renderer: introduce destroy callback

Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
diff --git a/src/noop-renderer.c b/src/noop-renderer.c
index 24660ec..a0b1679 100644
--- a/src/noop-renderer.c
+++ b/src/noop-renderer.c
@@ -68,7 +68,7 @@
 {
 }
 
-WL_EXPORT void
+static void
 noop_renderer_destroy(struct weston_compositor *ec)
 {
 	free(ec->renderer);
@@ -91,6 +91,7 @@
 	renderer->create_surface = noop_renderer_create_surface;
 	renderer->surface_set_color = noop_renderer_surface_set_color;
 	renderer->destroy_surface = noop_renderer_destroy_surface;
+	renderer->destroy = noop_renderer_destroy;
 	ec->renderer = renderer;
 
 	return 0;