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/tools/misc/units/default.nix

@@ -0,0 +1,47 @@
+{
+  stdenv,
+  lib,
+  fetchurl,
+  readline,
+  enableCurrenciesUpdater ? true,
+  pythonPackages ? null
+}:
+
+assert enableCurrenciesUpdater -> pythonPackages != null;
+
+stdenv.mkDerivation rec {
+  pname = "units";
+  version = "2.21";
+
+  src = fetchurl {
+    url = "mirror://gnu/units/${pname}-${version}.tar.gz";
+    sha256 = "sha256-bD6AqfmAWJ/ZYqWFKiZ0ZCJX2xxf1bJ8TZ5mTzSGy68=";
+  };
+
+  pythonEnv = pythonPackages.python.withPackages(ps: [
+    ps.requests
+  ]);
+
+  buildInputs = [ readline ]
+    ++ lib.optionals enableCurrenciesUpdater [
+      pythonEnv
+    ]
+  ;
+  prePatch = ''
+    substituteInPlace units_cur \
+      --replace "#!/usr/bin/env python" ${pythonEnv}/bin/python
+  '';
+  postInstall = ''
+    cp units_cur ${placeholder "out"}/bin/
+  '';
+
+  doCheck = true;
+
+  meta = with lib; {
+    description = "Unit conversion tool";
+    homepage = "https://www.gnu.org/software/units/";
+    license = [ licenses.gpl3Plus ];
+    platforms = platforms.all;
+    maintainers = [ maintainers.vrthra ];
+  };
+}