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

diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py
index 5d496c6..ecb6049 100644
--- a/Lib/test/test_ssl.py
+++ b/Lib/test/test_ssl.py
@@ -5,6 +5,7 @@
 import unittest.mock
 from test import support
 from test.support import socket_helper
+from test.support import threading_helper
 import socket
 import select
 import time
@@ -4429,7 +4430,7 @@
 
         # Ignore expected SSLError in ConnectionHandler of ThreadedEchoServer
         # (it is only raised sometimes on Windows)
-        with support.catch_threading_exception() as cm:
+        with threading_helper.catch_threading_exception() as cm:
             server = ThreadedEchoServer(context=server_context, chatty=False)
             with server:
                 with client_context.wrap_socket(socket.socket(),
@@ -4750,11 +4751,11 @@
     if support.is_resource_enabled('network'):
         tests.append(NetworkedTests)
 
-    thread_info = support.threading_setup()
+    thread_info = threading_helper.threading_setup()
     try:
         support.run_unittest(*tests)
     finally:
-        support.threading_cleanup(*thread_info)
+        threading_helper.threading_cleanup(*thread_info)
 
 if __name__ == "__main__":
     test_main()