pgsql: Add comments warning against generalizing default_with_oids.

Add comments warning against generalizing default_with_oids.

pg_dump has historically assumed that default_with_oids affects only plain
tables and not other relkinds. Conceivably we could make it apply to some
newly invented relkind if we did so from the get-go, but changing the
behavior for existing object types will break existing dump scripts.
Add code comments warning about this interaction.

Also, make sure that default_with_oids doesn't cause parse_utilcmd.c to
think that CREATE FOREIGN TABLE will create an OID column. I think this is
only a latent bug right now, since we don't allow UNIQUE/PKEY constraints
in CREATE FOREIGN TABLE, but it's better to be consistent and future-proof.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/0bd11d9711b88e72d2022e25b9227c480aca4978

Modified Files
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src/backend/commands/tablecmds.c | 8 ++++++++
src/backend/parser/parse_utilcmd.c | 13 ++++++++++++-
2 files changed, 20 insertions(+), 1 deletion(-)