Use "win32" for sys.platform on Win64 instead of "win32" because:
1. While it may be confusing to the Python scriptor on Win64 that he has to
   check for win*32*, that is something that he will learn the first time. It
   is better than the alternative of the scriptor happily using "win64" and
   then that code not running on Win32 for no good reason.
2. The main question is: is Win64 so much more like Win32 than different from
   it that the common-case general Python programmer should not ever have to
   make the differentiation in his Python code. Or, at least, enough so that
   such differentiation by the Python scriptor is rare enough that some other
   provided mechanism is sufficient (even preferable). Currently the answer
   is yes. Hopefully MS will not change this answer.