util-linux: pass libxcrypt, so sulogin gets built

Util-linux does not fail when crypt() isn't available. It just doesn't
build sulogin, which in turn breaks the initrd-builder for the
systemd-stage-1 tests.

pkgs/os-specific/linux/util-linux/default.nix

···
 { lib, stdenv, fetchurl, pkg-config, zlib, shadow
 , capabilitiesSupport ? true
 , libcap_ng
+, libxcrypt
 , ncursesSupport ? true
 , ncurses
 , pamSupport ? true
···
   nativeBuildInputs = [ pkg-config ]
     ++ lib.optionals translateManpages [ po4a ];
 
-  buildInputs = [ zlib ]
+  buildInputs = [ zlib libxcrypt ]
     ++ lib.optionals pamSupport [ pam ]
     ++ lib.optionals capabilitiesSupport [ libcap_ng ]
     ++ lib.optionals ncursesSupport [ ncurses ]