Set SO_REUSEADDR on layout test server sockets on non-Windows systems

Tools/Scripts/webkitpy/layout_tests/servers/server_base.py

 # Copyright (C) 2011 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 243 matching lines @@
                     raise
                 _log.debug("Server NOT running on %d: %s" % (port, e))
                 return False
             finally:
                 s.close()
         return True
 
     def _check_that_all_ports_are_available(self):
         for mapping in self._mappings:
             s = socket.socket()
-            # s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+            if not self._platform.is_win():
+                s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
             port = mapping['port']
             try:
                 s.bind(('localhost', port))
             except IOError, e:
                 if e.errno in (errno.EALREADY, errno.EADDRINUSE):
                     raise ServerError('Port %d is already in use.' % port)
                 elif self._platform.is_win() and e.errno in (errno.WSAEACCES,):  # pylint: disable=E1101
                     raise ServerError('Port %d is already in use.' % port)
                 else:
                     raise
             finally:
                 s.close()
         _log.debug('all ports are available')