Re: Additional role attributes && superuser review

Attached is an initial patch for review and discussion that takes a swing at changing the catalog representation.

This patch includes:

* int64 (C) to int8 (SQL) mapping for genbki.

* replace all role attributes columns in pg_authid with single int64 column named rolattr.

* update CreateRole and AlterRole to use rolattr.

* update all has_*_privilege functions to check rolattr.

* builtin SQL function 'has_role_attribute' that takes a role oid and text name of the attribute as input and returns a boolean.

Items not currently addressed:

* New syntax - more discussion needs to occur around these potential changes.  Specifically, how would CREATE USER/ROLE be affected?  I suppose it is OK to keep it as WITH <attribute_or_capability>, though if ALTER ROLE is modified to have ADD | DROP CAPABILITY for consistency would WITH CAPABILITY <value,...>, make more sense for CREATE?  At any rate, I think there is obviously much more discussion that needs to be had.

* Documentation - want to gain feedback on implementation prior to making changes.

* Update regression tests, rules test for system_views - want to gain feedback on approach to handling pg_roles, etc. before updating.

Also, what would be the community preference on tracking these attached/proposed changes?  Should I create a separate entry in the next CF for this item (seems prudent) or would it be preferred to keep it attached to the current 'new attributes' CF entry?