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/security/paperkey/default.nix

@@ -0,0 +1,34 @@
+{ fetchurl, lib, stdenv }:
+
+stdenv.mkDerivation rec {
+  pname = "paperkey";
+  version = "1.6";
+
+  src = fetchurl {
+    url = "https://www.jabberwocky.com/software/paperkey/${pname}-${version}.tar.gz";
+    sha256 = "1xq5gni6gksjkd5avg0zpd73vsr97appksfx0gx2m38s4w9zsid2";
+  };
+
+  postPatch = ''
+    for a in checks/*.sh ; do
+      substituteInPlace $a \
+        --replace /bin/echo echo
+    done
+  '';
+
+  enableParallelBuilding = true;
+
+  meta = with lib; {
+    description = "Store OpenPGP or GnuPG on paper";
+    longDescription = ''
+      A reasonable way to achieve a long term backup of OpenPGP (GnuPG, PGP, etc)
+      keys is to print them out on paper. Paper and ink have amazingly long
+      retention qualities - far longer than the magnetic or optical means that
+      are generally used to back up computer data.
+    '';
+    homepage = "https://www.jabberwocky.com/software/paperkey/";
+    license = licenses.gpl2;
+    platforms = platforms.unix;
+    maintainers = with maintainers; [ skeidel ];
+  };
+}