Re-visit freeze_support block

[mattwthompson]

          This is more of a remark than a review comment, but I have never needed to use this on Linux. The [Python docs](https://docs.python.org/3/library/multiprocessing.html#multiprocessing.freeze_support) say it should only be needed on Windows and "has no effect when invoked on any [other] operating system," so I'm surprised you've needed it too. I don't think it hurts to include it, I was just curious and finally looked it up.

Originally posted by @ntBre in #68 (comment)