sdl12-compat: lowercase 'opengl32'

SDL Commits
1 
From 7848987cbd5c15caefbc74c88476d70d247419f8 Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Fri, 11 Jun 2021 07:29:00 +0300
Subject: [PATCH] lowercase 'opengl32'

---
 CMakeLists.txt | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index d1309f0..200acb6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -98,8 +98,8 @@ if(SDL12TESTS)
     if(OpenGL_FOUND)
       set(HAVE_OPENGL_DEFINE "HAVE_OPENGL")
       if(WIN32)
-        set(OPENGL_gl_LIBRARY "OpenGL32")
-        set(OPENGL_opengl_LIBRARY "OpenGL32")
+        set(OPENGL_gl_LIBRARY "opengl32")
+        set(OPENGL_opengl_LIBRARY "opengl32")
       endif()
     endif()