Fixing this port only seems to require adding the missing supplementary go networking libraries which can be found here:

https://github.com/golang/net

Copying the libraries under the correct directory allows the port to compile and install. /usr/local/go/src/golang.org/x/net  
I had to manually create the golang.org and x directories and then included the network libraries there. As show below:

% ls /usr/local/go/src/golang.org/net

AUTHORS         bpf             icmp            lif             trace
CONTRIBUTING.md codereview.cfg  idna            nettest         webdav
CONTRIBUTORS    context         internal        netutil         websocket
LICENSE         dict            ipv4            proxy           xsrftoken
PATENTS         html            ipv6            publicsuffix
README          http2           lex             route

Hopefully, the maintainer can fix the broken port with this new information.

Thanks