Non-OSX supported code in rosmaster.util

[hawesie]

This is more of a heads-up for future installers than an issue with this repo.

ros/ros_comm#1207 means that recent installs are broken at runtime (not compile time). The symptoms are that everything comes up fine but some nodes cannot actually communicate.

The failure is pretty much silent just looking at node output. However roswtf reports ERROR The following nodes should be connected but aren't for many nodes and you can see

    state = transport._connection[1].sock.getsockopt(socket.SOL_TCP, socket.TCP_INFO)
AttributeError: 'module' object has no attribute 'TCP_INFO'

in your logs.

The PR ros/ros_comm#1211 fixed this for me.