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/tools/misc/chruby/default.nix

@@ -0,0 +1,44 @@
+{ stdenv, lib, fetchFromGitHub, runCommand, rubies ? null }:
+
+let
+  rubiesEnv = runCommand "chruby-env" { preferLocalBuild = true; } ''
+    mkdir $out
+    ${lib.concatStrings
+        (lib.mapAttrsToList (name: path: "ln -s ${path} $out/${name}\n") rubies)}
+  '';
+
+in stdenv.mkDerivation rec {
+  pname = "chruby";
+
+  version = "0.3.9";
+
+  src = fetchFromGitHub {
+    owner = "postmodern";
+    repo = "chruby";
+    rev = "v${version}";
+    sha256 = "1894g6fymr8kra9vwhbmnrcr58l022mcd7g9ans4zd3izla2j3gx";
+  };
+
+  patches = lib.optionalString (rubies != null) [
+    ./env.patch
+  ];
+
+  postPatch = lib.optionalString (rubies != null) ''
+    substituteInPlace share/chruby/chruby.sh --replace "@rubiesEnv@" ${rubiesEnv}
+  '';
+
+  installPhase = ''
+    mkdir $out
+    cp -r bin $out
+    cp -r share $out
+  '';
+
+  meta = with lib; {
+    description = "Changes the current Ruby";
+    homepage = "https://github.com/postmodern/chruby";
+    license = licenses.mit;
+    maintainers = with maintainers; [ cstrahan ];
+    mainProgram = "chruby-exec";
+    platforms = platforms.unix;
+  };
+}

pkgs/development/tools/misc/chruby/env.patch

@@ -0,0 +1,12 @@
+diff --git a/share/chruby/chruby.sh b/share/chruby/chruby.sh
+--- a/share/chruby/chruby.sh
++++ b/share/chruby/chruby.sh
+@@ -1,7 +1,7 @@
+ CHRUBY_VERSION="0.3.8"
+ RUBIES=()
+ 
+-for dir in "$PREFIX/opt/rubies" "$HOME/.rubies"; do
++for dir in @rubiesEnv@; do
+ 	[[ -d "$dir" && -n "$(ls -A "$dir")" ]] && RUBIES+=("$dir"/*)
+ done
+ unset dir