sdl12-compat: cmake: attempt to fix the stupid osx opengl linkage issue (again.)

SDL Commits
1 
From f227a5a0da8a6ab12d8365ad4024067bfc28d270 Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Mon, 14 Jun 2021 03:10:20 +0300
Subject: [PATCH] cmake: attempt to fix the stupid osx opengl linkage issue
 (again.)

---
 CMakeLists.txt | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index ff38cc4..7d4d6f1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -96,14 +96,14 @@ if(SDL12TESTS)
     endif()
 
     find_package(OpenGL COMPONENTS OpenGL)
-    if(OpenGL_FOUND)
-      set(OPENGL_FOUND 1)
-    endif()
     if(OPENGL_FOUND)
       set(HAVE_OPENGL_DEFINE "HAVE_OPENGL")
       if(WIN32)
         set(OPENGL_gl_LIBRARY "opengl32")
         set(OPENGL_opengl_LIBRARY "opengl32")
+      elseif(APPLE)
+        set(OPENGL_gl_LIBRARY "-Wl,-framework,OpenGL")
+        set(OPENGL_opengl_LIBRARY "-Wl,-framework,OpenGL")
       endif()
     endif()