Python 3.8 new deprecations

[Robin Becker]

Marius Gedminas has kindly been doing some work with reportlab and python 3.8a1

He reports this new deprecation warning from a c extension build

DeprecationWarning: PY_SSIZE_T_CLEAN will be required for '#' formats

Currently we build the extensions for 2.7 3.4-3.7 Windows 32 & 64 MacOS and linux.

His patch is changing several ints to Py_ssize_t after defining PY_SSIZE_T_CLEAN.

Can anyone say which versions/runtimes this is needed for or can I just assume it has no effect in early versions.
-- 
Robin Becker