De-duplicating the tree

Hi all

Now that more and more packages share spec files and often more across the
different OS versions, if not (yet) across Pg versions, I think it's worth
looking at how to reduce the manual copy&paste involved in doing simple
updates. It's error prone and tedious, and it shouldn't really be necessary.

Since I presume the build scripts etc are pretty heavily reliant on the
current tree structure and there's a lot of legacy that might still need
rebuilding one day, I'd like to symlink everything shared so that the build
system doesn't get upset. I've checked that mock won't be upset, you just
pass --symlink-dereference when building the srpm. If symlinks upset
whatever the build scripts are used for the main repo tree it should be
pretty trivial to tweak them to make them follow symlinks.

I'm thinking of starting with moving specs etc into per-version common/
dirs, like

rpm/redhat/9.5/repmgr/EL-6/repmgr.spec
=> rpm/redhat/9.5/repmgr/common/repmgr.spec

That'll bring the number of changes needed for many packages from 20+ down
to 3-5 for a common update.

I'll prep a branch for, say, repmgr showing how it'd look so you can test
your build scripts.

--
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services