Fix for actisense-serial not starting because open() blocks

First time with canboat & Actisense NGT-1 and actisense-serial would not start.

I traced it down to open(device, O_RDWR | O_NOCTTY) never returning. After a bit of Googling I tried adding O_NONBLOCK and it did start working, got data out all the way to n2kd.

I am using the Actisense FTDI drivers on OS X 10.8.4.

Is this solution universal? Don't really understandwhat causes it, I have very meager C skills and no experience with ftdi or ttys, so if there is a better way to fix the issue please let me know and I'll educate myself.