pgsql: Dump foreign keys on partitioned tables

Dump foreign keys on partitioned tables

The patch that ended up as commit 3de241dba86f ("Foreign keys on
partitioned tables") lacked pg_dump tests, so the pg_dump code that was
there to support it inadvertently stopped working when in later
development I modified the backend code not to emit pg_trigger rows for
the partitioned table itself.

Bug analysis and code fix is by Michaël.  I (Álvaro) added the test.

Reported-by: amul sul <sulamul@gmail.com>
Co-authored-by: Michaël Paquier <michael@paquier.xyz>
Co-authored-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/CAAJ_b94n=UsNVhgs97vCaWEZAMe-tGDRVuZ73oePQH=eaJKGSA@mail.gmail.com

Branch
------
REL_11_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/2af39c39df94096ecc593f5a162947e1e994cab3

Modified Files
--------------
src/bin/pg_dump/pg_dump.c        |  7 ++++++-
src/bin/pg_dump/t/002_pg_dump.pl | 19 +++++++++++++++++++
2 files changed, 25 insertions(+), 1 deletion(-)