sdl2-compat: Build with -fvisibility=hidden only for Mac/Unix (not e.g. for MinGW.)

SDL Commits
1 
From 73617c5bd056bc863d16111b7a9730af5c2c3243 Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Tue, 29 Nov 2022 23:47:02 +0300
Subject: [PATCH] Build with -fvisibility=hidden only for Mac/Unix (not e.g.
 for MinGW.)

---
 CMakeLists.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0cde4a9..552768c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -126,7 +126,7 @@ set(EXTRA_CFLAGS )
 if(CMAKE_C_COMPILER_ID MATCHES "Clang|GNU")
   set(EXTRA_CFLAGS "${EXTRA_CFLAGS} -Wall")
   check_c_compiler_flag(-fvisibility=hidden HAVE_FVISIBILITY_HIDDEN)
-  if(HAVE_FVISIBILITY_HIDDEN)
+  if(HAVE_FVISIBILITY_HIDDEN AND (APPLE OR UNIX))
     set(EXTRA_CFLAGS "${EXTRA_CFLAGS} -fvisibility=hidden")
   endif()
   check_c_compiler_flag(-Wdeclaration-after-statement HAVE_WDECLARATION_AFTER_STATEMENT)