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/networking/easyrsa/2.x.nix

@@ -0,0 +1,47 @@
+{ lib
+, stdenv
+, fetchFromGitHub
+, autoreconfHook
+, makeWrapper
+, gnugrep
+, openssl
+}:
+
+stdenv.mkDerivation rec {
+  pname = "easyrsa";
+  version = "2.2.0";
+
+  src = fetchFromGitHub {
+    owner = "OpenVPN";
+    repo = "easy-rsa";
+    rev = "v${version}";
+    sha256 = "sha256-zTdk8mv+gC/SHK813wZ6CWZf9Jm2XkKfAPU3feFpAkY=";
+  };
+
+  preBuild = ''
+    mkdir -p $out/share/easy-rsa
+  '';
+
+  nativeBuildInputs = [ autoreconfHook makeWrapper ];
+  buildInputs = [ gnugrep openssl ];
+
+  # Make sane defaults and patch default config vars
+  postInstall = ''
+    cp $out/share/easy-rsa/openssl-1.0.0.cnf $out/share/easy-rsa/openssl.cnf
+    for prog in $(find "$out/share/easy-rsa" -executable -type f); do
+      makeWrapper "$prog" "$out/bin/$(basename $prog)" \
+        --set EASY_RSA "$out/share/easy-rsa" \
+        --set OPENSSL "${openssl.bin}/bin/openssl" \
+        --set GREP "${gnugrep}/bin/grep"
+    done
+    sed -i "/EASY_RSA=\|OPENSSL=\|GREP=/d" $out/share/easy-rsa/vars
+  '';
+
+  meta = with lib; {
+    description = "Simple shell based CA utility";
+    homepage = "https://openvpn.net/";
+    license = licenses.gpl2;
+    maintainers = [ maintainers.offline ];
+    platforms = platforms.linux;
+  };
+}