Message 64051 - Python tracker

doc\make.bat, used to build the docs under Windows, retains the
hardcoded pydoc.hhp name when building htmlhelp. Now that the help files
are built as <release>.chm this file no longer exists and the build fails.

The attached patch to make.bat builds the htmlhelp from within a
temporary Python session which picks the correct filename up from conf.py.