libpsl doesn't build on older versions of Mac OS X because it depends on python38

[Kenneth F. Cunningham]

I pushed the python38 fix I have been using the past four months or so.

It works, and should get you moving. It has been well tested.

Upstream is looking to see if they might do an official integration of a fix that follows their usual Makefile pattern, and if they do, this fix may not be needed in some future release of python.

Thanks to everyone for their reviews and looking things over.

For Chris, the patches have been restricted to ancient systems only, and cannot affect 10.6 or newer in any way, as requested.

Ken