Re: Replace uses of deprecated Python module distutils.sysconfig

I wrote:
> Based on the buildfarm results so far, the problem can be described
> as "some installations say /usr/local when they should have said /usr".
> I experimented with the attached delta patch and it fixes the problem
> on my Debian 9 image. (I don't know Python, so there may be a better
> way to do this.) We'd have to also bump the minimum 3.x version to
> 3.2, but that seems very unlikely to bother anyone.

I did a little more digging into this. The python2 package on
my Deb9 (actually Raspbian) system says it is 2.7.13, but
/usr/lib/python2.7/sysconfig.py is different from what I find in
a virgin Python 2.7.13 tarball, as per attached diff. I conclude
that somebody at Debian decided that Python should live under
/usr/local, and changed sysconfig.py to match, but then failed
to adjust the actual install scripts to agree, because there is
certainly nothing installed under /usr/local. (I don't know
enough about Debian packaging to find the smoking gun though;
what apt-get claims is the source package contains no trace of
this diff.) There's no sign of comparable changes in
/usr/lib/python3.5/sysconfig.py on the same machine, either.

So I think this can fairly be characterized as brain-dead packaging
error, and we should just hack around it as per my previous patch.

In other news, I switched prairiedog and gaur to python 3.2.

regards, tom lane