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/misc/empty/default.nix

@@ -0,0 +1,46 @@
+{ fetchzip, lib, stdenv, which }:
+
+stdenv.mkDerivation rec {
+  pname = "empty";
+  version = "0.6.21b";
+
+  src = fetchzip {
+    url = "mirror://sourceforge/${pname}/${pname}/${pname}-${version}.tgz";
+    sha256 = "1rkixh2byr70pdxrwr4lj1ckh191rjny1m5xbjsa7nqw1fw6c2xs";
+    stripRoot = false;
+  };
+
+  patches = [
+    ./0.6-Makefile.patch
+  ];
+
+  nativeBuildInputs = [ which ];
+
+  makeFlags = [ "PREFIX=$(out)" ];
+
+  postPatch = ''
+    rm empty
+  '';
+
+  meta = with lib; {
+    homepage = "http://empty.sourceforge.net";
+    description = "A simple tool to automate interactive terminal applications";
+    license = licenses.bsd3;
+    platforms = platforms.all;
+    longDescription = ''
+      The empty utility provides an interface to execute and/or interact with
+      processes under pseudo-terminal sessions (PTYs). This tool is definitely
+      useful in programming of shell scripts designed to communicate with
+      interactive programs like telnet, ssh, ftp, etc. In some cases empty can
+      be the simplest replacement for TCL/expect or other similar programming
+      tools because empty:
+
+      - can be easily invoked directly from shell prompt or script
+      - does not use TCL, Perl, PHP, Python or anything else as an underlying language
+      - is written entirely in C
+      - has small and simple source code
+      - can easily be ported to almost all UNIX-like systems
+    '';
+    maintainers = [ maintainers.djwf ];
+  };
+}