bpo-40275: Adding threading_helper submodule in test.support (GH-20263)

diff --git a/Lib/test/test_queue.py b/Lib/test/test_queue.py
index d88e28a..7b23699 100644
--- a/Lib/test/test_queue.py
+++ b/Lib/test/test_queue.py
@@ -7,6 +7,7 @@
 import unittest
 import weakref
 from test import support
+from test.support import threading_helper
 
 py_queue = support.import_fresh_module('queue', blocked=['_queue'])
 c_queue = support.import_fresh_module('queue', fresh=['_queue'])
@@ -63,7 +64,7 @@
                           block_func)
             return self.result
         finally:
-            support.join_thread(thread) # make sure the thread terminates
+            threading_helper.join_thread(thread) # make sure the thread terminates
 
     # Call this instead if block_func is supposed to raise an exception.
     def do_exceptional_blocking_test(self,block_func, block_args, trigger_func,
@@ -79,7 +80,7 @@
                 self.fail("expected exception of kind %r" %
                                  expected_exception_class)
         finally:
-            support.join_thread(thread) # make sure the thread terminates
+            threading_helper.join_thread(thread) # make sure the thread terminates
             if not thread.startedEvent.is_set():
                 self.fail("trigger thread ended but event never set")
 
@@ -484,7 +485,7 @@
                                       args=(q, results, sentinel))
                      for i in range(n_consumers)]
 
-        with support.start_threads(feeders + consumers):
+        with threading_helper.start_threads(feeders + consumers):
             pass
 
         self.assertFalse(exceptions)