SDL: Fix warnings: re-add enum forward declaration

SDL Commits
1 
From 381f99a3fde8ea4b28276607024db0dcffdb9f33 Mon Sep 17 00:00:00 2001
From: Sylvain <[EMAIL REDACTED]>
Date: Tue, 23 Nov 2021 10:58:04 +0100
Subject: [PATCH] Fix warnings: re-add enum forward declaration

---
 src/video/wayland/SDL_waylanddyn.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/video/wayland/SDL_waylanddyn.h b/src/video/wayland/SDL_waylanddyn.h
index aacfacf18e4..13b0884d076 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"