Yeah that isn’t really appropriate work talk. Can you ask him to just stop? If he refuses you could talk to a supervisor? However being white and male will make this far less effective unless you buddy up to the boss first.

He is way out of line pushing that shit on you in the workplace. Have a man to man conversation with him. After thinking about exactly how and what you should say. Calmly explain that you don't want to hear about his views on race and other political things. It isn't suitable for the workplace and that is all it has to be about. We're at work so let's work. You can have a work relationship but that is it.

You've got a bigger problem then a black supervisor who seems to be progressively loosing his marbles. Keep your head down, treat the guy with courtesy and focus on being proficient in your job. Collect your pay, pay off your debts, build up your savings. Then focus yourself on learning skills that can net you a bigger paycheck, ideally in a field that blacks likely don't pursue entry. Whatever field you're in, if a black guy is there, then it's safe to assume some females maybe as well. If this is the case the job, or field is probably a few years away from obsolescence. Make your gains and get the hell out before the layoffs begin.