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>

pkgs/development/python-modules/exdown/default.nix

@@ -0,0 +1,36 @@
+{ lib
+, buildPythonPackage
+, isPy27
+, fetchPypi
+, pythonOlder
+, importlib-metadata
+, pytestCheckHook
+}:
+
+buildPythonPackage rec {
+  pname = "exdown";
+  version = "0.9.0";
+  format = "pyproject";
+
+  disabled = isPy27;
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "sha256-r0SCigkUpOiba4MDf80+dLjOjjruVNILh/raWfvjXA0=";
+  };
+
+  propagatedBuildInputs = lib.optionals (pythonOlder "3.8") [ importlib-metadata ];
+
+  checkInputs = [
+    pytestCheckHook
+  ];
+
+  pythonImportsCheck = [ "exdown" ];
+
+  meta = with lib; {
+    description = "Extract code blocks from markdown";
+    homepage = "https://github.com/nschloe/exdown";
+    license = licenses.mit;
+    maintainers = with maintainers; [ SuperSandro2000 ];
+  };
+}