Check if IOWorkLoop/IOThread is active

Don't tell the NSA, but I'm trying to find a way to see if my microphone's being used. According to the research I have done, each audio device driver has one IOCommandGate and one IOWorkLoop. I think that calling IOWorkLoop's getWorkThread will give me access to the work loop's work thread.

My thinking is that if this work thread is running, then a program is using my sound card.