SDL: Fixed building with older libdrm headers

From 8949de3978a360c04dbf9e9b4b7d7b6b4f86be5a Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Wed, 26 Jun 2024 12:18:43 -0700
Subject: [PATCH] Fixed building with older libdrm headers

---
 src/video/kmsdrm/SDL_kmsdrmvideo.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/video/kmsdrm/SDL_kmsdrmvideo.h b/src/video/kmsdrm/SDL_kmsdrmvideo.h
index 738165e923369..71d195ac6bab0 100644
--- a/src/video/kmsdrm/SDL_kmsdrmvideo.h
+++ b/src/video/kmsdrm/SDL_kmsdrmvideo.h
@@ -33,6 +33,10 @@
 #include <gbm.h>
 #include <EGL/egl.h>
 
+#ifndef DRM_MODE_FB_MODIFIERS
+#define DRM_MODE_FB_MODIFIERS	2
+#endif
+
 #ifndef DRM_MODE_PAGE_FLIP_ASYNC
 #define DRM_MODE_PAGE_FLIP_ASYNC    2
 #endif