Build process documentation? Also patches to make it easier to build individual packages

Hi

When I had to rebuild PostGIS 2.5 for EL-6 on Pg12 for a user, I found that
the current build process for the repo appears to be undocumented. At least
anywhere I could find in the repo, main pgdg yum site, and wiki entrypoint.

It looks like builds have transitioned to koji?
Given ./scripts/kojimachines/syncscripts/buildpackage.sh etc?

Is there any chance I can request a short README of a couple of paragraphs
added to the root of the repo that lists what's in each important
directory, points to the important URLs, and mentions how the packages are
built?

Would you be interested in accepting a sample definition for a container
image to build/rebuild individual packages with too? To save others time in
future if they need to do so? If you don't want to, that's fine, I can
publish it separately.

On a side note: some spec files do not parse without additional macros so
"yum builddep" cannot process them unless a definition for
%pgmajorversion is added in ~/.rpmmacros . EL-6's yum builddep doesn't have
a --define option to use at the command line. So in order to "yum builddep"
those spec files I had to first

echo '%pgmajorversion 12' >> /root/.rpmmacros

in my build container. Hope this helps someone else.

--
Craig Ringer http://www.2ndQuadrant.com/
2ndQuadrant - PostgreSQL Solutions for the Enterprise