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/hydra/common.nix

@@ -0,0 +1,48 @@
+{ system, ... }:
+{
+  baseConfig = { pkgs, ... }: let
+    trivialJob = pkgs.writeTextDir "trivial.nix" ''
+     { trivial = builtins.derivation {
+         name = "trivial";
+         system = "${system}";
+         builder = "/bin/sh";
+         allowSubstitutes = false;
+         preferLocalBuild = true;
+         args = ["-c" "echo success > $out; exit 0"];
+       };
+     }
+    '';
+
+    createTrivialProject = pkgs.stdenv.mkDerivation {
+      name = "create-trivial-project";
+      dontUnpack = true;
+      buildInputs = [ pkgs.makeWrapper ];
+      installPhase = "install -m755 -D ${./create-trivial-project.sh} $out/bin/create-trivial-project.sh";
+      postFixup = ''
+        wrapProgram "$out/bin/create-trivial-project.sh" --prefix PATH ":" ${pkgs.lib.makeBinPath [ pkgs.curl ]} --set EXPR_PATH ${trivialJob}
+      '';
+    };
+  in {
+    virtualisation.memorySize = 2048;
+    time.timeZone = "UTC";
+    environment.systemPackages = [ createTrivialProject pkgs.jq ];
+    services.hydra = {
+      enable = true;
+      # Hydra needs those settings to start up, so we add something not harmfull.
+      hydraURL = "example.com";
+      notificationSender = "example@example.com";
+      extraConfig = ''
+        email_notification = 1
+      '';
+    };
+    services.postfix.enable = true;
+    nix = {
+      distributedBuilds = true;
+      buildMachines = [{
+        hostName = "localhost";
+        systems = [ system ];
+      }];
+      settings.substituters = [];
+    };
+  };
+}