Move CompareType to separate header file
We'll want to make use of it in more places, and we'd prefer to not
have to include all of primnodes.h everywhere.
Author: Mark Dilger <mark.dilger@enterprisedb.com>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Discussion: https://www.postgresql.org/message-id/flat/
E72EAA49-354D-4C2E-8EB9-
255197F55330@enterprisedb.com