pgsql: Keep stats up to date for partitioned tables

Keep stats up to date for partitioned tables

In the long-going saga for analyze on partitioned tables, one thing I
missed while reverting 0827e8af70f4 is the maintenance of analyze count
and last analyze time for partitioned tables. This is a mostly trivial
change that enables users assess the need for invoking manual ANALYZE on
partitioned tables.

This patch, posted by Justin and modified a bit by me (Álvaro), can be
mostly traced back to Hosoya-san, though any problems introduced with
the scissors are mine.

Backpatch to 14, in line with 6f8127b73901.

Co-authored-by: Yuzuko Hosoya <yuzukohosoya(at)gmail(dot)com>
Co-authored-by: Justin Pryzby <pryzby(at)telsasoft(dot)com>
Co-authored-by: Álvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>
Reported-by: Justin Pryzby <pryzby(at)telsasoft(dot)com>
Discussion: https://postgr.es/m/20210816222810.GE10479@telsasoft.com

Branch
------
REL_14_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/e1efc5b465c844969a0ed0d07e1364f3ce424d8c

Modified Files
--------------
src/backend/commands/analyze.c | 37 +++++++++++++++++++++++++------------
src/backend/postmaster/pgstat.c | 11 ++++++++---
2 files changed, 33 insertions(+), 15 deletions(-)