This add the complement to T6185. In T6185, an 'inclusive' mask was added to derive, from the active config, the subtree of sections to be passed to config-sync; it is useful to have a generic 'exclusive' mask, as well, to then exclude paths of system-specific data, for example ethernet hw-id or address. It is worthwhile to develop this as a general tool, as it will have other uses. In addition, several supporting functions were developed that will also be of general use.