###### Motivation for this change
Update to latest upstream version
###### Things done
* [ ] Tested using sandboxing ([nix.useSandbox](http://nixos.org/nixos/manual/options.html#opt-nix.useSandbox) on NixOS, or option `sandbox` in [`nix.conf`](http://nixos.org/nix/manual/#sec-conf-file) on non-NixOS linux)
* Built on platform(s)
* [x] NixOS
* [ ] macOS
* [ ] other Linux distributions
* [ ] Tested via one or more NixOS test(s) if existing and applicable for the change (look inside [nixos/tests](https://github.com/NixOS/nixpkgs/blob/master/nixos/tests))
* [ ] Tested compilation of all pkgs that depend on this change using `nix-shell -p nix-review --run "nix-review wip"`
* [x] Tested execution of all binary files (usually in `./result/bin/`)
* [ ] Determined the impact on package closure size (by running `nix path-info -S` before and after)
* [ ] Ensured that relevant documentation is up to date
* [x] Fits [CONTRIBUTING.md](https://github.com/NixOS/nixpkgs/blob/master/.github/CONTRIBUTING.md).
###### Notify maintainers
cc @worldofpeace @tfc @jtraue
A disabled nscd breaks nss module loading on NixOS, and systemd without
its nss modules doesn't really work either - instead of silently
disabling its nss modules if nscd is disabled, let the assertion in
nsswitch handle this.
nixos/modules/config/nsswitch.nix uses `passwdArray` for both `passwd`
and `group`, but when moving this into the systemd module in
c0995d22eed1a19ac9442c8460c18dd6a4c389b7, it didn't get split
appropriately.
nixos/modules/config/nsswitch.nix uses `passwdArray` for both `passwd`
and `group`, but when moving this into the google-oslogin module in
4b71b6f8fa5f7b06ea5d0dd37d44a73757c7f142, it didn't get split
appropriately.
nixos/modules/config/nsswitch.nix uses `passwdArray` for both `passwd`
and `group`, but when moving this into the sss module in
edddc7c82a848f1b1f23344a338b5d56b38178c0, it didn't get split
appropriately.
