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/X11/xvkbd/default.nix

@@ -0,0 +1,38 @@
+{ lib, stdenv, fetchurl, libXt, libXaw, libXtst
+, libXi, libXpm, pkg-config, xorgproto, Xaw3d }:
+
+stdenv.mkDerivation rec {
+  pname = "xvkbd";
+  version = "4.1";
+  src = fetchurl {
+    url = "http://t-sato.in.coocan.jp/xvkbd/xvkbd-${version}.tar.gz";
+    sha256 = "1x5yldv9y99cw5hzzs73ygdn1z80zns9hz0baa355r711zghfbcm";
+  };
+
+  nativeBuildInputs = [ pkg-config ] ;
+  buildInputs = [ libXt libXaw libXtst xorgproto libXi Xaw3d libXpm ];
+
+  makeFlags = [
+    # avoid default libXt location
+    "appdefaultdir=${placeholder "out"}/share/X11/app-defaults"
+    "datarootdir=${placeholder "out"}/share"
+  ];
+
+  preInstall = ''
+    # workaround absence of libXt in $DESTDIR location.
+    mkdir -p $out/share/X11
+  '';
+
+  meta = with lib; {
+    description = "Virtual keyboard for X window system";
+    longDescription = ''
+      xvkbd is a virtual (graphical) keyboard program for X Window System which provides
+      facility to enter characters onto other clients (softwares) by clicking on a
+      keyboard displayed on the screen.
+    '';
+    homepage = "http://t-sato.in.coocan.jp/xvkbd";
+    license = licenses.gpl2Plus;
+    maintainers = [ maintainers.bennofs ];
+    platforms = platforms.linux;
+  };
+}