Add a few tests for pydoc.

This is a modified version of a patch proposed by Humberto Diogenes
in the discussion of issue1883.

I will merge manually this change into the py3k branch: the tests must be adapted.

Lib/test/test_sundry.py

@@ -90,7 +90,6 @@ class TestUntestedModules(unittest.TestCase):
             import posixfile
             import pstats
             import py_compile
-            import pydoc
             import rexec
             import rlcompleter
             import sched