pg_pwd trigger to be removed

Because of the problems that were pointed out, I'm inclined to remove the
pg_pwd updating trigger again. I can offer you the non-initdb requiring
variant (just remove the trigger definition in initdb) or the
clean-sweeping one (remove the trigger function from the backend). Okay,
the first one will require some sort of intervention as well, eventually,
but you see the difference.

My new take on the situation is actually that there shouldn't be a reason
to tinker with the systems catalogs period. In the case of pg_shadow
that's not entirely possible (catupd and trace can't be adjusted
otherwise), but that can be fixed (not now). After all they're called
*system* catalogs. If someone thinks they can rename a table by updating
pg_class.relname -- good night!

-- 
Peter Eisentraut                  Sernanders väg 10:115
peter_e@gmx.net                   75262 Uppsala
http://yi.org/peter-e/            Sweden