Replace remaining uses of "whitelist".

Instead describe the action that the list effects, or just use "list"
where the meaning is obvious from context.

Author: Dagfinn Ilmari Mannsåker <ilmari@ilmari.org>
Discussion: https://postgr.es/m/20200615182235.x7lch5n6kcjq4aue%40alap3.anarazel.de
