Move all of NixOS to nixos/ in preparation of the repository merge

nixos/modules/security/rtkit.nix

@@ -0,0 +1,39 @@
+# A module for ‘rtkit’, a DBus system service that hands out realtime
+# scheduling priority to processes that ask for it.
+
+{ config, pkgs, ... }:
+
+with pkgs.lib;
+
+{
+
+  options = {
+
+    security.rtkit.enable = mkOption {
+      default = false;
+      description = ''
+        Whether to enable the RealtimeKit system service, which hands
+        out realtime scheduling priority to user processes on
+        demand. For example, the PulseAudio server uses this to
+        acquire realtime priority.
+      '';
+    };
+
+  };
+
+
+  config = mkIf config.security.rtkit.enable {
+
+    environment.systemPackages = [ pkgs.rtkit ];
+
+    services.dbus.packages = [ pkgs.rtkit ];
+
+    users.extraUsers = singleton
+      { name = "rtkit";
+        uid = config.ids.uids.rtkit;
+        description = "RealtimeKit daemon";
+      };
+
+  };
+
+}