nixos/powerdns, nixos/pdns-recurser: Symlink configuration into /etc

This places a symlink to the running configuration where the admin
tools expect it, allowing users to control the powerdns server or
recursor without manually specifying a config file.

Changed files
+4
nixos
modules
services
+2
nixos/modules/services/networking/pdns-recursor.nix
···
config = mkIf cfg.enable {
+
environment.etc."powerdns-recursor".source = configDir;
+
services.pdns-recursor.settings = mkDefaultAttrs {
local-address = cfg.dns.address;
local-port = cfg.dns.port;
+2
nixos/modules/services/networking/powerdns.nix
···
config = mkIf cfg.enable {
+
environment.etc.powerdns.source = finalConfigDir;
+
systemd.packages = [ pkgs.pdns ];
systemd.services.pdns = {