Commit 8b08f7d4 added a relkind for local partitioned indexes, but
failed to add it to pg_class's list of possible relkinds.  Repair.

Author: Peter Geoghegan, Michaël Paquier
Discussion: https://postgr.es/m/CAH2-WzkOKptQiE51Bh4_xeEHhaBwHkZkGtKizrFMgEkfUuRRQg@mail.gmail.com