Don't create relfilenode for relations without storage

Don't create relfilenode for relations without storage

Some relation kinds had relfilenode set to some non-zero value, but
apparently the actual files did not really exist because creation was
prevented elsewhere.  Get rid of the phony pg_class.relfilenode values.

Catversion bumped, but only because the sanity_test check will fail if
run in a system initdb'd with the previous version.

Reviewed-by: Kyotaro HORIGUCHI, Michael Paquier
Discussion: https://postgr.es/m/20181206215552.fm2ypuxq6nhpwjuc@alvherre.pgsql