arptables: re-enable for static

Add a small patch to re-enable arptables for static builds.
The dlfcn.h is a stray include for a past attempt at loadable plugins
but the code is disabled so there's no need for it.

Also add hash file.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>