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/xkbvalidate/default.nix

@@ -0,0 +1,15 @@
+{ lib, runCommandCC, libxkbcommon }:
+
+runCommandCC "xkbvalidate" {
+  buildInputs = [ libxkbcommon ];
+  meta = {
+    description = "NixOS tool to validate X keyboard configuration";
+    license = lib.licenses.mit;
+    platforms = lib.platforms.unix;
+    maintainers = [ lib.maintainers.aszlig ];
+  };
+} ''
+  mkdir -p "$out/bin"
+  $CC -std=c11 -Wall -pedantic -lxkbcommon ${./xkbvalidate.c} \
+    -o "$out/bin/xkbvalidate"
+''