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/security/su-exec/default.nix

@@ -0,0 +1,26 @@
+{ lib, stdenv, fetchFromGitHub }:
+
+stdenv.mkDerivation rec {
+  pname = "su-exec";
+  version = "0.2";
+
+  src = fetchFromGitHub {
+    owner  = "ncopa";
+    repo   = "su-exec";
+    rev    = "v${version}";
+    sha256 = "12vqlnpv48cjfh25sn98k1myc7h2wiv5qw2y2awgp6sipzv88abv";
+  };
+
+  installPhase = ''
+    mkdir -p $out/bin
+    cp -a su-exec $out/bin/su-exec
+  '';
+
+  meta = with lib; {
+    description = "switch user and group id and exec";
+    homepage    = "https://github.com/ncopa/su-exec";
+    license     = licenses.mit;
+    maintainers = with maintainers; [ zimbatm ];
+    platforms   = platforms.linux;
+  };
+}