sdl12-compat: cmake: Fix Windows build...again.

From 8323fed73071b32073c6eb9ca00b7860827d2f32 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Thu, 10 Jun 2021 14:32:12 -0400
Subject: [PATCH] cmake: Fix Windows build...again.

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

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c897b7d..0744f9c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -97,6 +97,10 @@ if(SDL12TESTS)
     find_package(OpenGL COMPONENTS OpenGL)
     if(OpenGL_FOUND)
       set(HAVE_OPENGL_DEFINE "HAVE_OPENGL")
+      if(WIN32)
+        set(${OPENGL_gl_LIBRARY} "OpenGL32")
+        set(${OPENGL_opengl_LIBRARY} "OpenGL32")
+      endif()
     endif()
 
     macro(test_program _NAME _SRCS)