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_builtin.py b/Lib/test/test_builtin.py
index e5c9770..505da70 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -1219,9 +1219,7 @@
         self.assertRaises(ValueError, zip, BadSeq(), BadSeq())
 
 def test_main():
-    suite = unittest.TestSuite()
-    suite.addTest(unittest.makeSuite(BuiltinTest))
-    test.test_support.run_suite(suite)
+    test.test_support.run_unittest(BuiltinTest)
 
 if __name__ == "__main__":
     test_main()