and adapt to 3737965249c changes.

Contains the only fix: heal segfault introduced in 11.7 and 12.2

commit 8f68671
Author: Arseny Sher sher-ars@yandex.ru
Date: Thu Apr 2 21:00:26 2020 +0300

[PGPRO-3725] zero out garbage in append_rel_array if we allocate it.

Since 1d9056f563f3 (who uses AppendRelInfo* existence as a mark this rel is
child) in 11.7 this led to (known) random segfaults.

Port to Postgres 12.

Prevent double expand partitioned table by built-in inheritance and pg_pathman's one.

Minor fixes.

Minor fixes.

Fix SELECT FOR SHARE/UPDATE with multilevel partitioning, cache fixes, other minor things.

Minor fixes

Minor fixes

Minor fix