Debian package support

[msqr]

I'd like to be able to include this extension in environments where a Debian binary package would be helpful, instead of having to build from source.

I researched a bit how to do this, and got the build working using debhelper in a feature/debian branch. See the debian/README for how I set up the build environment.

I added a deb recipe to the Makefile like this:

deb:
	make clean
	git archive --format tar --prefix=aggs-for-vecs-$(EXTENSION_VERSION)/ feature/debian |gzip >../aggs-for-vecs_$(EXTENSION_VERSION).orig.tar.gz
	pg_buildext updatecontrol
	make -f debian/rules debian/control
	dh clean
	make all
	dpkg-buildpackage -us -uc

You can see it's hard-coded to build from the feature/debian branch at the moment. I think that would eventually change to a tag or perhaps master.

I originally created the debian build files via

dh_make_pgxs -v 1.3.0 -h https://github.com/pjungwir/aggs_for_vecs

This turned the underscores in the project name to dashes, so the build packages are named like postgresql-12-aggs-for-vecs_1.3.0-1_amd64.deb (as Debian package names aren't allowed to have underscores, I think).

In any case, I'm new to building Debian packages like this, so I'm not sure if everything is configured correctly. If you have feedback, or would like me to submit a PR, I'm happy to do that.

[pjungwir]

I think a deb is a great idea. Just today I was using apt to install first-last-agg on Ubuntu to avoid compiling it on client machines. I don't see anything in that project to build the deb file, and the deb maintainer isn't the same as the extension author. That's too bad: it would have been nice to see their approach re Makefile rules and git branches. Oh well. I think a PR would be nice though. Thanks!

[msqr]

Great! I'll submit a PR shortly.