unudhcpd

In 65038ce2 the logic for also checksum checking pkgs in the systemd
repo was dropped when the logic was moved from build_changed_aports.py,
this re-introduces that logic so that checksums for packages in the
systemd repo are also checked.

Part-of: https://gitlab.postmarketos.org/postmarketos/pmaports/-/merge_requests/6404