SDL: cmake: don't cache HAVE_3DNOW value

From 46d85fd5a4076198b5a1bcaac6d0e81962a10cda Mon Sep 17 00:00:00 2001
From: Anonymous Maarten <[EMAIL REDACTED]>
Date: Fri, 25 Nov 2022 23:22:17 +0100
Subject: [PATCH] cmake: don't cache HAVE_3DNOW value

---
 CMakeLists.txt | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 56fbee69e120..94e2a19f5eb3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -783,8 +783,9 @@ if(SDL_ASSEMBLY)
             void *p = 0;
             _m_prefetch(p);
             return 0;
-          }" HAVE_3DNOW)
-      if(HAVE_3DNOW)
+          }" CPU_SUPPORTS_3DNOW)
+      if(CPU_SUPPORTS_3DNOW)
+        set(HAVE_3DNOW TRUE)
         list(APPEND EXTRA_CFLAGS "-m3dnow")
       endif()
       set(CMAKE_REQUIRED_FLAGS ${ORIG_CMAKE_REQUIRED_FLAGS})