Combine the functionality of test_support.run_unittest()
and test_support.run_classtests() into run_unittest()
and use it wherever possible.

Also don't use "from test.test_support import ...", but
"from test import test_support" in a few spots.

From SF patch #662807.
diff --git a/Lib/test/test_hmac.py b/Lib/test/test_hmac.py
index f36db4e..4f1454f 100644
--- a/Lib/test/test_hmac.py
+++ b/Lib/test/test_hmac.py
@@ -103,12 +103,12 @@
             "Hexdigest of copy doesn't match original hexdigest.")
 
 def test_main():
-    suite = unittest.TestSuite()
-    suite.addTest(unittest.makeSuite(TestVectorsTestCase))
-    suite.addTest(unittest.makeSuite(ConstructorTestCase))
-    suite.addTest(unittest.makeSuite(SanityTestCase))
-    suite.addTest(unittest.makeSuite(CopyTestCase))
-    test_support.run_suite(suite)
+    test_support.run_unittest(
+        TestVectorsTestCase,
+        ConstructorTestCase,
+        SanityTestCase,
+        CopyTestCase
+    )
 
 if __name__ == "__main__":
     test_main()