bpo-40275: Use new test.support helper submodules in tests (GH-21449)

diff --git a/Lib/test/test_signal.py b/Lib/test/test_signal.py
index 45553a6..c656790 100644
--- a/Lib/test/test_signal.py
+++ b/Lib/test/test_signal.py
@@ -9,6 +9,7 @@
 import time
 import unittest
 from test import support
+from test.support import os_helper
 from test.support.script_helper import assert_python_ok, spawn_python
 try:
     import _testcapi
@@ -154,7 +155,7 @@
             signal.set_wakeup_fd(signal.SIGINT, False)
 
     def test_invalid_fd(self):
-        fd = support.make_bad_fd()
+        fd = os_helper.make_bad_fd()
         self.assertRaises((ValueError, OSError),
                           signal.set_wakeup_fd, fd)