WireGuard for FreeBSD

[Jason A. Donenfeld]

We now have a release, so the full instructions for the packages are:

1. wireguard-tools, providing wg(8) and wg-quick(8)
Runtime dependencies: bash, wireguard-go
Buildtime dependencies: gmake, c compiler, libc
Build: gmake -C src/tools WITH_WGQUICK=yes
Install: gmake -C src/tools PREFIX=/usr/local install
URL: https://git.zx2c4.com/WireGuard/snapshot/WireGuard-0.0.20180524.tar.xz

2. wireguard-go
Runtime dependencies: libc
Buildtime dependencies: gmake, go, dep
Build: gmake
Install: gmake PREFIX=/usr/local install
URL: https://git.zx2c4.com/wireguard-go/snapshot/wireguard-go-0.0.20180524.tar.xz

I believe decke is already working on a port in his repository.