In pg_upgrade, improve error reporting when the number of relation objects does not match between the old and new clusters.
In pg_upgrade, improve error reporting when the number of relation
objects does not match between the old and new clusters.

Backpatch to 9.2.

postmind-net/postgres-xl,postmind-net/postgres-xl,kmjungersen/PostgresXL,snaga/postgres-xl,arcivanov/postgres-xl,kmjungersen/PostgresXL,arcivanov/postgres-xl,arcivanov/postgres-xl,snaga/postgres-xl,snaga/postgres-xl,kmjungersen/PostgresXL,arcivanov/postgres-xl,postmind-net/postgres-xl,arcivanov/postgres-xl,postmind-net/postgres-xl,snaga/postgres-xl,postmind-net/postgres-xl,snaga/postgres-xl,arcivanov/postgres-xl,kmjungersen/PostgresXL,kmjungersen/PostgresXL