cleanup redundant S_IFDIR declaration

Author: weltling

ext/standard/file.c

@@ -122,9 +122,6 @@ php_file_globals file_globals;
 # include <wchar.h>
 #endif
 
-#ifndef S_ISDIR
-# define S_ISDIR(mode)	(((mode)&S_IFMT) == S_IFDIR)
-#endif
 /* }}} */
 
 #define PHP_STREAM_TO_ZVAL(stream, arg) \