bpo-40275: Use new test.support helper submodules in tests (GH-21315)

diff --git a/Lib/test/test_linecache.py b/Lib/test/test_linecache.py
index 375d9c4..cfc6ba8 100644
--- a/Lib/test/test_linecache.py
+++ b/Lib/test/test_linecache.py
@@ -6,6 +6,7 @@
 import tempfile
 import tokenize
 from test import support
+from test.support import os_helper
 
 
 FILENAME = linecache.__file__
@@ -44,7 +45,7 @@
         with tempfile.NamedTemporaryFile(delete=False) as fp:
             self.file_name = fp.name
             fp.write(self.file_byte_string)
-        self.addCleanup(support.unlink, self.file_name)
+        self.addCleanup(os_helper.unlink, self.file_name)
 
 
 class GetLineTestsGoodData(TempFile):
@@ -124,10 +125,10 @@
         self.assertEqual(empty, [])
 
     def test_no_ending_newline(self):
-        self.addCleanup(support.unlink, support.TESTFN)
-        with open(support.TESTFN, "w") as fp:
+        self.addCleanup(os_helper.unlink, os_helper.TESTFN)
+        with open(os_helper.TESTFN, "w") as fp:
             fp.write(SOURCE_3)
-        lines = linecache.getlines(support.TESTFN)
+        lines = linecache.getlines(os_helper.TESTFN)
         self.assertEqual(lines, ["\n", "def f():\n", "    return 3\n"])
 
     def test_clearcache(self):
@@ -150,8 +151,8 @@
     def test_checkcache(self):
         getline = linecache.getline
         # Create a source file and cache its contents
-        source_name = support.TESTFN + '.py'
-        self.addCleanup(support.unlink, source_name)
+        source_name = os_helper.TESTFN + '.py'
+        self.addCleanup(os_helper.unlink, source_name)
         with open(source_name, 'w') as source:
             source.write(SOURCE_1)
         getline(source_name, 1)