make building with Codewarrior 7 possible

src/skel/crossplatform.h

@@ -21,7 +21,11 @@ char *_strdate(char *buf);
 // As long as WITHWINDOWS isn't defined / <Windows.h> isn't included, we only need type definitions so let's include <IntSafe.h>.
 // NOTE: It's perfectly fine to include <Windows.h> here, but it can increase build size and time in *some* conditions, and maybe substantially in future if we'll use crossplatform.h more.
 #ifndef _INC_WINDOWS
-    #include <IntSafe.h>
+	#ifndef __MWERKS__
+		#include <IntSafe.h>
+	#else
+		#include <Windows.h>
+	#endif
 #endif
 #if defined RW_D3D9 || defined RWLIBS
 #include "win.h"