I've installed v7.3.2 from your RedHat 7.3 RPM on a Linux 7.x system. I create a table:
create table EN(
rec_id char( 2 ) check( rec_id = 'EN' ),
...
);
and then do in psql:
xxx> \d EN
ERROR: Relation "pg_relcheck" does not exist
This error happens on all tables that I define (all have the same type of constraint).
This worked fine in v7.0.2.