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/text/papertrail/default.nix

@@ -0,0 +1,31 @@
+{ lib, stdenv, bundlerEnv, ruby, bundlerUpdateScript }:
+
+let
+  papertrail-env = bundlerEnv {
+    name = "papertrail-env";
+    inherit ruby;
+    gemfile = ./Gemfile;
+    lockfile = ./Gemfile.lock;
+    gemset = ./gemset.nix;
+  };
+in stdenv.mkDerivation {
+  pname = "papertrail";
+  version = (import ./gemset.nix).papertrail.version;
+
+  dontUnpack = true;
+
+  installPhase = ''
+    mkdir -p $out/bin
+    ln -s ${papertrail-env}/bin/papertrail $out/bin/papertrail
+  '';
+
+  passthru.updateScript = bundlerUpdateScript "papertrail";
+
+  meta = with lib; {
+    description = "Command-line client for Papertrail log management service";
+    homepage    = "https://github.com/papertrail/papertrail-cli/";
+    license     = licenses.mit;
+    maintainers = with maintainers; [ nicknovitski ];
+    platforms   = ruby.meta.platforms;
+  };
+}