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/system/mcron/default.nix

@@ -0,0 +1,39 @@
+{ fetchurl, lib, stdenv, guile, which, ed, libtool }:
+
+stdenv.mkDerivation rec {
+  pname = "mcron";
+  version = "1.0.6";
+
+  src = fetchurl {
+    url = "mirror://gnu/mcron/mcron-${version}.tar.gz";
+    sha256 = "0yvrfzzdy2m7fbqkr61fw01wd9r2jpnbyabxhcsfivgxywknl0fy";
+  };
+
+  patches = [ ./install-vixie-programs.patch ];
+
+  # don't attempt to chmod +s files in the nix store
+  postPatch = ''
+    substituteInPlace makefile.in --replace "rwxs" "rwx"
+  '';
+
+  buildInputs = [ guile which ed libtool ];
+
+  doCheck = true;
+
+  meta = {
+    description = "Flexible implementation of `cron' in Guile";
+
+    longDescription = ''
+      The GNU package mcron (Mellor's cron) is a 100% compatible
+      replacement for Vixie cron.  It is written in pure Guile, and
+      allows configuration files to be written in scheme (as well as
+      Vixie's original format) for infinite flexibility in specifying
+      when jobs should be run.  Mcron was written by Dale Mellor.
+    '';
+
+    homepage = "https://www.gnu.org/software/mcron/";
+
+    license = lib.licenses.gpl3Plus;
+    platforms = lib.platforms.unix;
+  };
+}