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.
Why the strange name: the prefix is necessary to follow our own advice that
environment generators should have numerical prefixes. I also put -d- in the
name because otherwise the name was very easy to mistake with
systemd.environment-generator. This additional letter clarifies that this
on special generator that supports environment.d files.
v2:
- add example files to EXTRA_DIST
v3:
- rework for the new scheme where nothing is written to disk
v4:
- use separate dirs for system and user env generators
