Files which are installed as-is (any .service and other unit files, .conf
files, .policy files, etc), are left as is. My assumption is that SPDX
identifiers are not yet that well known, so it's better to retain the
extended header to avoid any doubt.
I also kept any copyright lines. We can probably remove them, but it'd nice to
obtain explicit acks from all involved authors before doing that.
For the search domain logic the order is highly relevant, hence make sure when collecting the various search domains to
add them to an ordered set, so that the order between search domains of a specific link is retained.
