leafnode: fix build with libxcrypt

pkgs/servers/news/leafnode/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchurl, pcre }:
+{ lib, stdenv, fetchurl, pcre, libxcrypt }:
 
 stdenv.mkDerivation {
   pname = "leafnode";
@@ -27,7 +27,7 @@ stdenv.mkDerivation {
       sed -i validatefqdn.c -e 's/int is_validfqdn(const char \*f) {/int is_validfqdn(const char *f) { return 1;/;'
   '';
 
-  buildInputs = [ pcre];
+  buildInputs = [ pcre libxcrypt ];
 
   meta = {
     homepage = "http://leafnode.sourceforge.net/";