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/mailhog.nix

@@ -0,0 +1,24 @@
+import ./make-test-python.nix ({ lib, ... }: {
+  name = "mailhog";
+  meta.maintainers = with lib.maintainers; [ jojosch ];
+
+  nodes.machine = { pkgs, ... }: {
+    services.mailhog.enable = true;
+
+    environment.systemPackages = with pkgs; [ swaks ];
+  };
+
+  testScript = ''
+    start_all()
+
+    machine.wait_for_unit("mailhog.service")
+    machine.wait_for_open_port("1025")
+    machine.wait_for_open_port("8025")
+    machine.succeed(
+        'echo "this is the body of the email" | swaks --to root@example.org --body - --server localhost:1025'
+    )
+    assert "this is the body of the email" in machine.succeed(
+        "curl --fail http://localhost:8025/api/v2/messages"
+    )
+  '';
+})