The configured sysconfdir is used to look for nix.conf, so it needs to be /etc, and not $out/etc, so we separate out the place where shell profile files are installed, which is the only other place sysconfdir is at all used. See https://git.lix.systems/lix-project/lix/issues/231#issuecomment-1989 for more info. Change-Id: Idbed8ba82e711b8a9d6b6127904befa27d58e279