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/system/r10k/default.nix

@@ -0,0 +1,23 @@
+{ lib, bundlerApp, bundlerUpdateScript, makeWrapper, git, gnutar, gzip }:
+
+bundlerApp {
+  pname = "r10k";
+  gemdir = ./.;
+  exes = [ "r10k" ];
+
+  buildInputs = [ makeWrapper ];
+
+  postBuild = ''
+    wrapProgram $out/bin/r10k --prefix PATH : ${lib.makeBinPath [ git gnutar gzip ]}
+  '';
+
+  passthru.updateScript = bundlerUpdateScript "r10k";
+
+  meta = with lib; {
+    description = "Puppet environment and module deployment";
+    homepage    = "https://github.com/puppetlabs/r10k";
+    license     = licenses.asl20;
+    maintainers = with maintainers; [ zimbatm manveru nicknovitski ];
+    platforms = platforms.unix;
+  };
+}