[WireGuard] OpenWRT package for wireguard

[Jason A. Donenfeld]

There's also a lot to be done with -flto. I was working on getting
this working last year but ran into some snags. I'll give it another
try.

There's also the more bootleg version of running with -fwhole-program
and then using the __visible attribute on the module init/cleanup
functions. I don't know if this would actually work properly though.