libweston: Allow compositor-wayland to use wl_surface_damage_buffer

wl_surface_damage_buffer landed ages ago, but in order for GL to
use it the client must bind a wl_compositor version >= 4 (the
version where damage_buffer was introduced).

This patch updates the bind version and allows
eglSwapBuffersWithDamage to actually use the provided damage
rectangles instead of performing full surface damage.

Reviewed-by: Daniel Stone <daniels@collabora.com>

libweston/compositor-wayland.c

@@ -2319,7 +2319,8 @@ registry_handle_global(void *data, struct wl_registry *registry, uint32_t name,
 	if (strcmp(interface, "wl_compositor") == 0) {
 		b->parent.compositor =
 			wl_registry_bind(registry, name,
-					 &wl_compositor_interface, 1);
+					 &wl_compositor_interface,
+					 MIN(version, 4));
 	} else if (strcmp(interface, "zxdg_shell_v6") == 0) {
 		b->parent.xdg_shell =
 			wl_registry_bind(registry, name,