Extensions do not live in schemas. pg_extension.extnamespace is *not* the
schema that the extension belongs to, unlike most "*namespace" fields in
catalog tables.

These patches were written by Daniel Gustafsson, I just squashed and
rebased them.

* Add missing 5.0 object procedure declarations

Commit 7ec83119 implemented support for 5.0 objects in
binary upgrade, but missed adding the procedure declarations to
pg_upgrade due to a mismerge.

* Fix opclass Oid preassignment function

The function was erroneously pulling the wrong argument for the
namespace Oid resulting in failed Oid lookups during synchronization.

* Add support functions for pg_amop tuples

The gpoptutils module was removed during the 5.0 development cycle
and won't be available in the new cluster. Add exception for upgrades
from 4.3.

There was previously no support added for CREATE OPERATOR in the
binary upgrade code, add Oid pre-assignment support for operators.

Constraints are not uniquely identified by namespace and name alone.
It's possible to have multiple constraints with the same name, but attached
to different tables or domains. So include parent relation and domain OIDs
in the key.

This was uncovered by a regression test in the TINC test suite. Move the
OID consistency tests from TINC into the normal regression test suite, to
have test coverage for this.

The binary-upgrade mode in pg_dump which was backported in a previous commit
is here extended to handle Greenplum clusters. The gist of the changes are
to extend the Oid dumping to cover all object types as upstream PostgreSQL
only covers types. The changes include:

Make "pg_dump --binary-upgrade" connect in utility mode, it's supposed to
be run against a single segment server. Also make pg_dump work against 4.3
clusters as the binary-upgrade mode will be used with pg_upgrade on the old
cluster in the upgrade.

Dump Oids for all object types in binary upgrade mode. In PostgreSQL only
type Oids are dumped in binary upgrade mode, for Greenplum however we need
to dump the Oids for all objects that require Oid dispatching (see
oid_dispatch.c for details). Inject calls in the dump file for the Oid
dispatcher to preassign Oids during restore.

For partitioned tables, the Oids for each child table as well as their
constraints are added to the dump file. The distributioncheck for
partitions is skipped when restoring during binary upgrade. The
distribution info is not available in the segments so during binary
upgrade we cant enforce this check.

Avoid creating array type for AO relation types, it's not useful for anything
and only grows the catalog for no use.

Heikki Linnakangas, Daniel Gustafsson and Dave Cramer

This commit just brings in the upstream code for pg_upgrade and
pg_upgrade_support as is, with no changes. Subsequent work will change
it to work for Greenplum. The goal is to make it usable for upgrading
from Greenplum 4.3 to 5.0.

pg_upgrade_support is a crucial part of pg_upgrade, but lives in a
separate directory to make the build easier.