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_itertools.py b/Lib/test/test_itertools.py
index 4c506d0..2a60959 100644
--- a/Lib/test/test_itertools.py
+++ b/Lib/test/test_itertools.py
@@ -162,9 +162,7 @@
 def test_main(verbose=None):
     import test_itertools
     suite = unittest.TestSuite()
-    for testclass in (TestBasicOps,
-                          ):
-        suite.addTest(unittest.makeSuite(testclass))
+    suite.addTest(unittest.makeSuite(TestBasicOps))
     test_support.run_suite(suite)
     test_support.run_doctest(test_itertools, verbose)