Don't lose partitioned table reltuples=0 after relhassubclass=f.

ANALYZE sets relhassubclass=f when a partitioned table no longer has
partitions.  An ANALYZE doing that proceeded to apply the inplace update
of pg_class.reltuples to the old pg_class tuple instead of the new
tuple, losing that reltuples=0 change if the ANALYZE committed.
Non-partitioning inheritance trees were unaffected.  Back-patch to v14,
where commit 375aed36ad introduced
maintenance of partitioned table pg_class.reltuples.

Reported by Alexander Lakhin.

Discussion: https://postgr.es/m/a295b499-dcab-6a99-c06e-01cf60593344@gmail.com

src/backend/commands/analyze.c

@@ -637,7 +637,11 @@ do_analyze_rel(Relation onerel, VacuumParams *params,
 
 		visibilitymap_count(onerel, &relallvisible, NULL);
 
-		/* Update pg_class for table relation */
+		/*
+		 * Update pg_class for table relation.  CCI first, in case acquirefunc
+		 * updated pg_class.
+		 */
+		CommandCounterIncrement();
 		vac_update_relstats(onerel,
 							relpages,
 							totalrows,
@@ -672,6 +676,7 @@ do_analyze_rel(Relation onerel, VacuumParams *params,
 		 * Partitioned tables don't have storage, so we don't set any fields
 		 * in their pg_class entries except for reltuples and relhasindex.
 		 */
+		CommandCounterIncrement();
 		vac_update_relstats(onerel, -1, totalrows,
 							0, hasindex, InvalidTransactionId,
 							InvalidMultiXactId,