Re: not null constraints, again

> Here's v11, which I intended to commit today, but didn't get around to.
> CI is happy with it, so I'll probably do it tomorrow first thing.
>
v11 still has column_constraint versus table_constraint inconsistency.

create table t7 (a int generated by default as identity, constraint
foo not null a no inherit, b int);
create table t7 (a int generated by default as identity not null no
inherit, b int);
create table t8 (a serial, constraint foo1 not null a no inherit);
create table t8 (a serial not null no inherit, b int);

i solved this issue at [1],
that patch has one whitespace issue though.

what do you think?
[1]  https://postgr.es/m/CACJufxHgBsJrHyGJ0EQzi9XV+ZSozNDcUJ5sg-f5Wk+dGCYZMg@mail.gmail.com