Make amcanorder independent of amconsistentordering
Follow-up to commit
af4002b381d: Make amconsistentordering not depend
on amcanorder. Although they are related, they are independent
properties.
Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/E1tngY6-0000UL-2n%40gemulon.postgresql.org