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/xpra/update.sh

@@ -0,0 +1,5 @@
+#!/usr/bin/env nix-shell
+#!nix-shell -i bash -p curl perl common-updater-scripts
+
+version=$(curl https://xpra.org/src/ | perl -ne 'print "$1\n" if /xpra-([[:digit:].]+)\./' | sort -V | tail -n1)
+update-source-version xpra "$version"