uboot: (firmwareOdroidC2/C4) don't invoke patch tool, use patches = [] instead

https://github.com/NixOS/nixpkgs/blob/master/pkgs/stdenv/generic/setup.sh#L948
this can do it nicely.

Signed-off-by: Anton Arapov <anton@deadbeef.mx>

nixos/tests/common/auto.nix

@@ -0,0 +1,68 @@
+{ config, lib, ... }:
+
+with lib;
+
+let
+
+  dmcfg = config.services.xserver.displayManager;
+  cfg = config.test-support.displayManager.auto;
+
+in
+
+{
+
+  ###### interface
+
+  options = {
+
+    test-support.displayManager.auto = {
+
+      enable = mkOption {
+        default = false;
+        description = ''
+          Whether to enable the fake "auto" display manager, which
+          automatically logs in the user specified in the
+          <option>user</option> option.  This is mostly useful for
+          automated tests.
+        '';
+      };
+
+      user = mkOption {
+        default = "root";
+        description = "The user account to login automatically.";
+      };
+
+    };
+
+  };
+
+
+  ###### implementation
+
+  config = mkIf cfg.enable {
+
+    services.xserver.displayManager = {
+      lightdm.enable = true;
+      autoLogin = {
+        enable = true;
+        user = cfg.user;
+      };
+    };
+
+    # lightdm by default doesn't allow auto login for root, which is
+    # required by some nixos tests. Override it here.
+    security.pam.services.lightdm-autologin.text = lib.mkForce ''
+        auth     requisite pam_nologin.so
+        auth     required  pam_succeed_if.so quiet
+        auth     required  pam_permit.so
+
+        account  include   lightdm
+
+        password include   lightdm
+
+        session  include   lightdm
+    '';
+
+  };
+
+}