socket.py: fix close() method not to reference any globals

gevent/socket.py

@@ -314,7 +314,8 @@ class socket(object):
             self._wait(self._read_event)
         return socket(_sock=client_socket), address
 
-    def close(self,_closedsocket=_closedsocket, _delegate_methods=_delegate_methods, setattr=setattr):
+    def close(self, _closedsocket=_closedsocket, _delegate_methods=_delegate_methods,
+              setattr=setattr, cancel_wait_ex=cancel_wait_ex):
         # This function should not reference any globals. See Python issue #808164.
         self.hub.cancel_wait(self._read_event, cancel_wait_ex)
         self.hub.cancel_wait(self._write_event, cancel_wait_ex)