Fix warnings: re-add enum forward declaration
diff --git a/src/video/wayland/SDL_waylanddyn.h b/src/video/wayland/SDL_waylanddyn.h
index aacfacf..13b0884 100644
--- a/src/video/wayland/SDL_waylanddyn.h
+++ b/src/video/wayland/SDL_waylanddyn.h
@@ -42,6 +42,9 @@ struct libdecor_state;
struct libdecor_configuration;
struct libdecor_interface;
struct libdecor_frame_interface;
+enum libdecor_resize_edge;
+enum libdecor_capabilities;
+enum libdecor_window_state;
#include <stdint.h>
#include "wayland-cursor.h"