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

diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index 3bc1a3e..edb4ec0 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -26,10 +26,10 @@
 from types import AsyncGeneratorType, FunctionType
 from operator import neg
 from test import support
-from test.support import (
-    EnvironmentVarGuard, TESTFN, check_warnings, swap_attr, unlink,
-    maybe_get_event_loop_policy)
+from test.support import (swap_attr, maybe_get_event_loop_policy)
+from test.support.os_helper import (EnvironmentVarGuard, TESTFN, unlink)
 from test.support.script_helper import assert_python_ok
+from test.support.warnings_helper import check_warnings
 from unittest.mock import MagicMock, patch
 try:
     import pty, signal