Sdl12-compat: constructor and destructor attributes are for gcc only

SDL Commits
1 
From 913c891006ccf466280129508aac455466e09c1b Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Fri, 19 Feb 2021 17:47:00 +0300
Subject: [PATCH] constructor and destructor attributes are for gcc only.

---
 src/SDL12_compat.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/SDL12_compat.c b/src/SDL12_compat.c
index 91a9ec4..d42a9a3 100644
--- a/src/SDL12_compat.c
+++ b/src/SDL12_compat.c
@@ -836,6 +836,7 @@ LoadSDL20(void)
     return okay;
 }
 
+#if defined(__GNUC__)
 static void dllinit(void) __attribute__((constructor));
 static void dllinit(void)
 {
@@ -851,6 +852,13 @@ static void dllquit(void)
 {
     UnloadSDL20();
 }
+#elif defined(_MSC_VER) && defined(_WIN32)
+    #error Write me
+#elif defined(__WATCOMC__) && defined(__OS2__)
+    #error Write me
+#else
+    #error Please define your platform.
+#endif
 
 DECLSPEC const SDL_version * SDLCALL
 SDL_Linked_Version(void)