Eliminating pg_catalog.pg_rewrite.ev_attr

This was previously discussed here:

http://www.postgresql.org/message-id/flat/24836.1370713481@sss.pgh.pa.us#24836.1370713481@sss.pgh.pa.us

The attached patch implements what I think we agreed on.

To recap, ev_attr was present in pg_rewrite at the point that
Postgres95 version 1.01 source code was imported to version
control, with a default of -1 to mean "all columns".  It became
obsolete in 2002 with commit
95ef6a344821655ce4d0a74999ac49dd6af6d342, which went into
PostgreSQL version 7.3, removing the ability to define a rule on a
specific column; however, this column and over 100 lines of
vestigial code was left behind.  Later code was written as though 0
was used to mean "all columns", as is done elsewhere in the code,
although pre-existing code was not changed to match.  That
inconsistency didn't much matter since there was no way to define
anything which exercised the code, short of hacking the system
tables directly.

The patch removes the obsolete column from pg_rewrite, and all the
vestigial code I was able to find.  The justification for the patch
is to eliminate over 100 lines of code from an area which is
confusing enough without it.

Unless someone has an objection or thinks this needs to go through
the CF process, I will commit it tomorrow, with a catversion bump.

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company