build: Find Python the Autotools way
An added advantage to this is that it makes it really easy to build with Python 3, the same way other Autotools projects support it:
$ export PYTHON=/usr/bin/python3
$ ./configure
By the way, this builds perfectly fine with Python 3.
Is that something you want to support going forward? Or do you recommend downstreams build with Python 2 for now?
(note that quite a few downstream distributors are trying to remove Python 2 entirely)