pg_ctl is fragile

After an unclean shutdown (e.g. a kernel crash), pg_ctl isn't smart
enough to realize that it won't be able to successfully shut down the
postmaster:

$ pg_ctl -D /pgsql/data stop
/pgsql/bin/pg_ctl: line 269: kill: (2039) - No such process
waiting for postmaster to shut down................................................................ failed
pg_ctl: postmaster does not shut down

We should probably check the exit code produced by kill(1).

Cheers,

Neil

--
Neil Conway <neilc@samurai.com> || PGP Key ID: DB3C29FC