Cleanup of documentation change from #17860

Reformulated the textual change, and applied it to the docstring as well.
Issue #18377: Code cleanup in Python Launcher

This changeset fixes a number of compiler warnings in the Python Launcher
binary for OSX. It also cleans up whitespace usage in those sources.
Issue #18013: Fix cgi.FieldStorage to parse the W3C sample form.
#17198: Fix a NameError in the dbm module.  Patch by Valentina Mukhamedzhanova.