Commit 7e413a0f added that option to pg_dump, but neglected to teach
pg_dumpall how to pass it along.  Repair.

Author: Fabien Coelho
Reported-by: Peter Eisentraut
Reviewed-by: David Rowley
Discussion: https://postgr.es/m/45f50c59-ddbb-8cf2-eedb-81003f603528@2ndquadrant.com