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/mmdoc/default.nix

@@ -0,0 +1,38 @@
+{ lib
+, stdenv
+, fetchFromGitHub
+, cmark-gfm
+, xxd
+, fastJson
+, libzip
+, ninja
+, meson
+, pkg-config
+}:
+
+stdenv.mkDerivation rec {
+  pname = "mmdoc";
+  version = "0.9.1";
+
+  src = fetchFromGitHub {
+    owner = "ryantm";
+    repo = "mmdoc";
+    rev = version;
+    hash = "sha256-Lz2+vsXjz9BVOCI1vIrNTvZgh19OuvXEhnMw2QBZr1w=";
+  };
+
+  nativeBuildInputs = [ ninja meson pkg-config xxd ];
+
+  buildInputs = [ cmark-gfm fastJson libzip ];
+
+  doCheck = stdenv.isx86_64;
+
+  meta = with lib; {
+    broken = stdenv.isDarwin;
+    description = "Minimal Markdown Documentation";
+    homepage = "https://github.com/ryantm/mmdoc";
+    license = licenses.cc0;
+    maintainers = with maintainers; [ ryantm ];
+    platforms = platforms.unix;
+  };
+}