SDL: cmake: fix SDL_RENDER_GPU report at end of configuration

SDL Commits
1 
From 8ce2074d08ba385d88077fd07a45c2dc1126e5ec Mon Sep 17 00:00:00 2001
From: Anonymous Maarten <[EMAIL REDACTED]>
Date: Fri, 30 Aug 2024 13:35:13 +0200
Subject: [PATCH] cmake: fix SDL_RENDER_GPU report at end of configuration

---
 CMakeLists.txt | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9e288da675377..05411c9a542a2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2961,6 +2961,7 @@ if(SDL_GPU)
   endif()
   if(SDL_RENDER_GPU)
     set(SDL_VIDEO_RENDER_GPU 1)
+    set(HAVE_RENDER_GPU TRUE)
   endif()
 endif()