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/graphics/pngcrush/default.nix

@@ -0,0 +1,26 @@
+{ lib, stdenv, fetchurl, libpng }:
+
+stdenv.mkDerivation rec {
+  pname = "pngcrush";
+  version = "1.8.13";
+
+  src = fetchurl {
+    url = "mirror://sourceforge/pmt/pngcrush-${version}-nolib.tar.xz";
+    sha256 = "0l43c59d6v9l0g07z3q3ywhb8xb3vz74llv3mna0izk9bj6aqkiv";
+  };
+
+  makeFlags = [ "CC=${stdenv.cc.targetPrefix}cc" "LD=${stdenv.cc.targetPrefix}cc" ];      # gcc and/or clang compat
+
+  configurePhase = ''
+    sed -i s,/usr,$out, Makefile
+  '';
+
+  buildInputs = [ libpng ];
+
+  meta = {
+    homepage = "http://pmt.sourceforge.net/pngcrush";
+    description = "A PNG optimizer";
+    license = lib.licenses.free;
+    platforms = with lib.platforms; linux ++ darwin;
+  };
+}