Move weston_output_set_cursor into compositor-drm.c

First step towards moving hw cursor handling into compositor-drm.c a its
general overlay handling.
diff --git a/src/compositor.h b/src/compositor.h
index d4f85d4..4a36824 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -84,8 +84,6 @@
 	struct wl_list mode_list;
 
 	void (*repaint)(struct weston_output *output);
-	int (*set_hardware_cursor)(struct weston_output *output,
-				   struct weston_input_device *input);
 	void (*destroy)(struct weston_output *output);
 	void (*assign_planes)(struct weston_output *output);
 };
@@ -419,6 +417,9 @@
 weston_surface_damage(struct weston_surface *surface);
 
 void
+weston_surface_damage_below(struct weston_surface *surface);
+
+void
 weston_buffer_post_release(struct wl_buffer *buffer);
 
 uint32_t