pg_upgradecluster should use pg_upgrade if available

[Stuart Bishop]

A number of new utilities are available in /usr/lib/postgresql/x.x/bin, but don't have wrappers in the standard path.

pg_basebackup
pg_controldata
pg_resetxlog

maybes:

pg_ctl (may cause too much confusion with existing Debian pg_ctlcluster. Maybe pg_ctlcluster can be deprecated now?)
pg_upgrade (works direct on data directories, so wrapper maybe unsuitable as desired version may not be known. Symlink to pg_upgrade_9.1?)

[Martin Pitt (pitti)]

pg_basebackup was wrapped in postgresql-common 128, which is in precise. pg_controldata, pg_resetxlog, and pg_upgrade are server-side commands and thus are not really adequate for wrapping (only client-side programs are).

[Martin Pitt (pitti)]

The only thing that's left here is pg_upgrade, but that still won't work directly on the separate data dir layout that Debian/Ubuntu are using. However, pg_upgradecluster will be taught to use pg_upgrade soon, Peter is working on that. Retitling the bug for this.

[Martin Pitt (pitti)]

Note that you can now use "pg_upgradecluster --method upgrade" to use pg_upgrade. It is not the default yet, I'll switch it in the next Ubuntu release when 9.3 is the version that people upgrade from, and pg_upgrade has stabilized enough.