pgsql: Fix pg_dump for inherited validated not-null constraints

Fix pg_dump for inherited validated not-null constraints

When a child constraint is validated and the parent constraint it
derives from isn't, pg_dump must be coerced into printing the child
constraint; failing to do would result in a dump that restores the
constraint as not valid, which would be incorrect.

Co-authored-by: jian he <jian(dot)universality(at)gmail(dot)com>
Co-authored-by: Álvaro Herrera <alvherre(at)kurilemu(dot)de>
Reported-by: jian he <jian(dot)universality(at)gmail(dot)com>
Message-id: https://postgr.es/m/CACJufxGHNNMc0E2JphUqJMzD3=bwRSuAEVBF5ekgkG8uY0Q3hg@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/0e13b13d26e870cb18fe6ecf9f8697ddfcf2c740

Modified Files
--------------
src/bin/pg_dump/common.c | 26 ++++++++++++--
src/bin/pg_dump/pg_dump.c | 20 ++++++++---
src/bin/pg_dump/pg_dump.h | 1 +
src/bin/pg_dump/t/002_pg_dump.pl | 59 +++++++++++++++++++++++++++++--
src/test/regress/expected/constraints.out | 34 ++++++++++++++++++
src/test/regress/sql/constraints.sql | 18 ++++++++++
6 files changed, 149 insertions(+), 9 deletions(-)