xtest__server_close.py: remove unused import

--HG--
extra : transplant_source : %F43%1E%A6mh%01%A4%0Fs%CB%8D5%FF%16i%C1%40%0B%BD

greentest/xtest__server_close.py

 import unittest
 from gevent import socket
 import gevent
-from gevent.server import StreamServer
 import errno
 import os
 from test__server import SimpleStreamServer