This should make it all "Just Work"tm. We no longer need a Makefile
to do the installation. The point is, don't bother trying to use
/etc/cabal-install/srve.list as the global list. That's hard to do
because it involves installing that file, and we only want to do that
for global installs, so it's even more complex. Instead we should just
use cabal's facility to install data files. That way it ends up in
/usr/local/share/cabal-install-x.y/
or somewhere similar for a user install. But either way, cabal handles it.
The per-user config sill overrides this one, so it's still possible to edit
the list even if /usr/local/share/ is read-only. Also, we always use
$HOME/.cabal-install/ for the per-user config and package cache.
The one downside is that if an admin wants to use /etc/ and /var rather
than /root/.cabal-install/ then this is a tad harder. But the point is
at the moment it'll at least work for most people without fiddling,
including windows users.