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_queue.py b/Lib/test/test_queue.py
index 1636280..5f5a6ac 100644
--- a/Lib/test/test_queue.py
+++ b/Lib/test/test_queue.py
@@ -1,10 +1,10 @@
 # Some simple queue module tests, plus some failure conditions
 # to ensure the Queue locks remain stable.
 import Queue
-import threading
 import time
 import unittest
 from test import test_support
+threading = test_support.import_module('threading')
 
 QUEUE_SIZE = 5