pgsql: Add aggsortop column to pg_aggregate, so that MIN/MAX

Log Message:
-----------
Add aggsortop column to pg_aggregate, so that MIN/MAX optimization can
be supported for all datatypes. Add CREATE AGGREGATE and pg_dump support
too. Add specialized min/max aggregates for bpchar, instead of depending
on text's min/max, because otherwise the possible use of bpchar indexes
cannot be recognized.
initdb forced because of catalog changes.

Modified Files:
--------------
pgsql/doc/src/sgml:
catalogs.sgml (r2.99 -> r2.100)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/catalogs.sgml.diff?r1=2.99&r2=2.100)
pgsql/doc/src/sgml/ref:
create_aggregate.sgml (r1.31 -> r1.32)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/create_aggregate.sgml.diff?r1=1.31&r2=1.32)
pgsql/src/backend/catalog:
pg_aggregate.c (r1.72 -> r1.73)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/pg_aggregate.c.diff?r1=1.72&r2=1.73)
pgsql/src/backend/commands:
aggregatecmds.c (r1.23 -> r1.24)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/aggregatecmds.c.diff?r1=1.23&r2=1.24)
pgsql/src/backend/optimizer/plan:
planagg.c (r1.1 -> r1.2)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/plan/planagg.c.diff?r1=1.1&r2=1.2)
pgsql/src/backend/utils/adt:
varchar.c (r1.108 -> r1.109)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/varchar.c.diff?r1=1.108&r2=1.109)
pgsql/src/bin/pg_dump:
pg_dump.c (r1.405 -> r1.406)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_dump/pg_dump.c.diff?r1=1.405&r2=1.406)
pgsql/src/include/catalog:
catversion.h (r1.263 -> r1.264)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h.diff?r1=1.263&r2=1.264)
pg_aggregate.h (r1.49 -> r1.50)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_aggregate.h.diff?r1=1.49&r2=1.50)
pg_proc.h (r1.357 -> r1.358)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_proc.h.diff?r1=1.357&r2=1.358)
pgsql/src/include/utils:
builtins.h (r1.254 -> r1.255)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/builtins.h.diff?r1=1.254&r2=1.255)
pgsql/src/test/regress/expected:
oidjoins.out (r1.16 -> r1.17)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/oidjoins.out.diff?r1=1.16&r2=1.17)
opr_sanity.out (r1.57 -> r1.58)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/opr_sanity.out.diff?r1=1.57&r2=1.58)
pgsql/src/test/regress/sql:
oidjoins.sql (r1.16 -> r1.17)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/oidjoins.sql.diff?r1=1.16&r2=1.17)
opr_sanity.sql (r1.46 -> r1.47)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/opr_sanity.sql.diff?r1=1.46&r2=1.47)