SDL: Add CYGWIN support for DLL library check

From 5e1d8b8a6f130342520748b8e27c7f796a14f8bd Mon Sep 17 00:00:00 2001
From: Carlo Bramini <[EMAIL REDACTED]>
Date: Mon, 25 May 2026 15:32:06 +0200
Subject: [PATCH] Add CYGWIN support for DLL library check

(from https://github.com/libsdl-org/SDL_image/pull/747)
---
 cmake/macros.cmake | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cmake/macros.cmake b/cmake/macros.cmake
index afa0a3b5975617..3a651fcb91c18b 100644
--- a/cmake/macros.cmake
+++ b/cmake/macros.cmake
@@ -277,7 +277,7 @@ function(target_get_dynamic_library DEST TARGET)
   endif()
   if(result)
     string(TOLOWER "${result}" result_lower)
-    if(WIN32 OR OS2)
+    if(WIN32 OR OS2 OR CYGWIN)
       if(NOT result_lower MATCHES ".*dll")
         message(FATAL_ERROR "\"${result}\" is not a .dll library")
       endif()