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_trace.py b/Lib/test/test_trace.py
index 21e5ca9..ff6fc58 100644
--- a/Lib/test/test_trace.py
+++ b/Lib/test/test_trace.py
@@ -531,9 +531,11 @@
         no_jump_without_trace_function()
 
 def test_main():
-    test_support.run_unittest(TraceTestCase)
-    test_support.run_unittest(RaisingTraceFuncTestCase)
-    test_support.run_unittest(JumpTestCase)
+    test_support.run_unittest(
+        TraceTestCase,
+        RaisingTraceFuncTestCase,
+        JumpTestCase
+    )
 
 if __name__ == "__main__":
     test_main()