sdl12-compat: restrict DllMainCRTStartup to MinGW and MSVC builds

SDL Commits
1 
From 1d75774ed2a18bc0685efa513fd555f38b076ca6 Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Fri, 30 Apr 2021 14:01:10 +0300
Subject: [PATCH] restrict DllMainCRTStartup to MinGW and MSVC builds

---
 src/SDL12_compat.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/SDL12_compat.c b/src/SDL12_compat.c
index 2562bf9..4129752 100644
--- a/src/SDL12_compat.c
+++ b/src/SDL12_compat.c
@@ -991,7 +991,7 @@ static void dllquit(void)
     UnloadSDL20();
 }
 
-#elif defined(_WIN32)
+#elif defined(_WIN32) && (defined(_MSC_VER) || defined(__MINGW32__))
 #if defined(_MSC_VER) && !defined(__FLTUSED__)
 #define __FLTUSED__
 __declspec(selectany) int _fltused = 1;