systemd: remove unused null checks

, docbook_xml_dtd_45

}:

assert withResolved -> (libgcrypt != null && libgpg-error != null);

assert withImportd ->

(curl.dev != null && zlib != null && xz != null && libgcrypt != null

  && gnutar != null && gnupg != null && withCompression);

assert withEfi -> (gnu-efi != null);

assert withRemote -> lib.getDev curl != null;

assert withImportd -> withCompression;

assert withCoredump -> withCompression;

assert withHomed -> withCryptsetup;

assert withCryptsetup -> (cryptsetup != null);

let

  wantCurl = withRemote || withImportd;

  wantGcrypt = withResolved || withImportd;