Issue #7449, last part (11): fix many tests if thread support is disabled

 * Use try/except ImportError or test_support.import_module() to import thread
   and threading modules
 * Add @unittest.skipUnless(threading, ...) to testcases using threads
diff --git a/Lib/test/test_telnetlib.py b/Lib/test/test_telnetlib.py
index a04bc3f..fd5c6f7 100644
--- a/Lib/test/test_telnetlib.py
+++ b/Lib/test/test_telnetlib.py
@@ -1,11 +1,11 @@
 import socket
-import threading
 import telnetlib
 import time
 import Queue
 
 from unittest import TestCase
 from test import test_support
+threading = test_support.import_module('threading')
 
 HOST = test_support.HOST
 EOF_sigil = object()