Remove pg_class.relhaspkey
It is not used for anything internally, and it cannot be relied on for
external uses, so it can just be removed. To correct recommended way to
check for a primary key is in pg_index.
Discussion: https://www.postgresql.org/message-id/flat/
b1a24c6c-6913-f89c-674e-
0704f0ed69db@2ndquadrant.com