nixos/openntpd: Don't start until we have networking

This attempts to fix an issues where ntp is unable to resolve hostnames
because it came up before local nameservers or networking.

nixos/modules/services/networking/openntpd.nix

@@ -64,6 +64,8 @@ in
     systemd.services.openntpd = {
       description = "OpenNTP Server";
       wantedBy = [ "multi-user.target" ];
+      wants = [ "network-online.target" ];
+      after = [ "dnsmasq.service" "bind.service" "network-online.target" ];
       serviceConfig.ExecStart = "${package}/sbin/ntpd -d -f ${cfgFile} ${cfg.extraOptions}";
     };
   };