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/misc/nix-direnv/default.nix

@@ -0,0 +1,39 @@
+{ lib
+, stdenv
+, fetchFromGitHub
+, gnugrep
+, nix
+, enableFlakes ? null # deprecated
+}:
+stdenv.mkDerivation rec {
+  pname = "nix-direnv";
+  version = "2.1.0";
+
+  src = fetchFromGitHub {
+    owner = "nix-community";
+    repo = "nix-direnv";
+    rev = version;
+    sha256 = "sha256-PANJTaGdMvIPglgQCOs+fJc20ZnnHXx7rBdyoA4rQ0A=";
+  };
+
+  # Substitute instead of wrapping because the resulting file is
+  # getting sourced, not executed:
+  postPatch = ''
+    sed -i "1a NIX_BIN_PREFIX=${nix}/bin/" direnvrc
+    substituteInPlace direnvrc --replace "grep" "${gnugrep}/bin/grep"
+  '';
+
+  installPhase = ''
+    runHook preInstall
+    install -m500 -D direnvrc $out/share/nix-direnv/direnvrc
+    runHook postInstall
+  '';
+
+  meta = with lib; {
+    description = "A fast, persistent use_nix implementation for direnv";
+    homepage    = "https://github.com/nix-community/nix-direnv";
+    license     = licenses.mit;
+    platforms   = platforms.unix;
+    maintainers = with maintainers; [ mic92 bbenne10 ];
+  };
+}