seems that my last post didn't make it through. That's good
since the diff itself didn't covered the renaming of
pg_user.h to pg_shadow.h and it's new content.
Here it's again. The complete regression test passwd with
only some float diffs. createuser and destroyuser work.
pg_shadow cannot be read by ordinary user.
So if the relname is given to acldefault() in
utils/adt/acl.c, it can do a IsSystemRelationName() on it and
return ACL_RD instead of ACL_WORLD_DEFAULT.
Subject: [HACKERS] better access control error messages
This patch replaces the 'no such class or insufficient privilege' with
distinct error messages that tell you whether the table really doesn't
exist or whether access was denied.
