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/xcftools/default.nix

@@ -0,0 +1,41 @@
+{lib, stdenv, fetchurl, libpng, perl, gettext }:
+
+stdenv.mkDerivation rec {
+  pname = "xcftools";
+  version = "1.0.7";
+
+  src = fetchurl {
+    url = "http://henning.makholm.net/xcftools/xcftools-${version}.tar.gz";
+    sha256 = "19i0x7yhlw6hd2gp013884zchg63yzjdj4hpany011il0n26vgqy";
+  };
+
+  buildInputs = [ libpng perl gettext ];
+
+  patchPhase = ''
+    # Required if building with libpng-1.6, innocuous otherwise
+    substituteInPlace xcf2png.c         \
+      --replace png_voidp_NULL NULL     \
+      --replace png_error_ptr_NULL NULL
+
+    # xcfview needs mailcap and isn't that useful anyway
+    sed -i -e '/BINARIES/s/xcfview//' Makefile.in
+  '';
+
+  meta = {
+    homepage = "http://henning.makholm.net/software";
+    description = "Command-line tools for converting Gimp XCF files";
+    longDescription = ''
+      A set of fast command-line tools for extracting information from
+      the Gimp's native file format XCF.
+
+      The tools are designed to allow efficient use of layered XCF
+      files as sources in a build system that use 'make' and similar
+      tools to manage automatic processing of the graphics.
+
+      These tools work independently of the Gimp engine and do not
+      require the Gimp to even be installed.
+    '';
+    license = lib.licenses.gpl2;
+    platforms = lib.platforms.linux;
+  };
+}