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/compilers/mruby/default.nix

@@ -0,0 +1,34 @@
+{ lib, stdenv, ruby, bison, rake, fetchFromGitHub }:
+
+stdenv.mkDerivation rec {
+  pname = "mruby";
+  version = "3.1.0";
+
+  src = fetchFromGitHub {
+    owner   = "mruby";
+    repo    = "mruby";
+    rev     = version;
+    sha256  = "0gnzip7qfadnl0r1k8bpc9a6796sy503h77ggds02wrz7mpq32nf";
+  };
+
+  nativeBuildInputs = [ ruby bison rake ];
+
+  # Necessary so it uses `gcc` instead of `ld` for linking.
+  # https://github.com/mruby/mruby/blob/35be8b252495d92ca811d76996f03c470ee33380/tasks/toolchains/gcc.rake#L25
+  preBuild = if stdenv.isLinux then "unset LD" else null;
+
+  installPhase = ''
+    mkdir $out
+    cp -R include build/host/{bin,lib} $out
+  '';
+
+  doCheck = true;
+
+  meta = with lib; {
+    description = "An embeddable implementation of the Ruby language";
+    homepage = "https://mruby.org";
+    maintainers = [ maintainers.nicknovitski ];
+    license = licenses.mit;
+    platforms = platforms.unix;
+  };
+}