Re: NOT ENFORCED constraint feature

hi.
only applied v7-0001.

alter_table.sgml says we can specify enforceability
for  ALTER TABLE ADD column_constraint
and ALTER TABLE ADD column_constraint table_constraint.
but we didn't have a test for column_constraint in alter_table.sql

so segmental fault happened again:

create table tx(a int);
alter table tx add column b text collate "C" constraint cc check (a >
1) not enforced;
alter table tx add column b text collate "C" constraint cc check (b <>
'h') not enforced;
------------------------------------------------------------------------
errmsg("multiple ENFORCED/NOT ENFORCED clauses not allowed"),
never tested.
here are the tests:
CREATE TABLE t5(x int CHECK (x > 3) NOT ENFORCED enforced , b int);
CREATE TABLE t5(x int CHECK (x > 3) ENFORCED not enforced , b int);

------------------------------------------------------------------------
create foreign table with column_constraint, segmental fault also

reproduce:
DO $d$
    BEGIN
        EXECUTE $$CREATE SERVER loopback FOREIGN DATA WRAPPER postgres_fdw
            OPTIONS (dbname '$$||current_database()||$$',
                     port '$$||current_setting('port')||$$'
            )$$;
        EXECUTE $$CREATE SERVER loopback2 FOREIGN DATA WRAPPER postgres_fdw
            OPTIONS (dbname '$$||current_database()||$$',
                     port '$$||current_setting('port')||$$'
            )$$;
        EXECUTE $$CREATE SERVER loopback3 FOREIGN DATA WRAPPER postgres_fdw
            OPTIONS (dbname '$$||current_database()||$$',
                     port '$$||current_setting('port')||$$'
            )$$;
    END;
$d$;
CREATE USER MAPPING FOR CURRENT_USER SERVER loopback;
CREATE FOREIGN TABLE ft1 (c0 int constraint cc check (c0 > 1) not
enforced) SERVER loopback;