Merge branch 'rs/loose-object-cache-perffix'

The loose object cache used to optimize existence look-up has been updated. * rs/loose-object-cache-perffix: object-store: retire odb_load_loose_cache() object-store: use one oid_array per subdirectory for loose cache object-store: factor out odb_clear_loose_cache() object-store: factor out odb_loose_cache()