bpo-40275: Use new test.support helper submodules in tests (GH-21169)

diff --git a/Lib/test/test_lzma.py b/Lib/test/test_lzma.py
index 0f3af27..c2427f8 100644
--- a/Lib/test/test_lzma.py
+++ b/Lib/test/test_lzma.py
@@ -9,7 +9,11 @@
 import unittest
 
 from test.support import (
-    _4G, TESTFN, import_module, bigmemtest, run_unittest, unlink
+    _4G, bigmemtest, run_unittest
+)
+from test.support.import_helper import import_module
+from test.support.os_helper import (
+    TESTFN, unlink
 )
 
 lzma = import_module("lzma")