This mistake cost him more than a stroke. Ralph Lauren has ended its sponsorship of Justin Thomas because the No. 3-ranked golfer muttered a homophobic slur after missing a putt. Thomas, 27, missed a short putt on the 4th hole of the Sentry Tournament of Champions in Hawaii last Saturday. While walking to his tap-in bogey putt, Thomas muttered the slur, which was picked up by course microphones. Thomas apologized for the slur after his round. “First off, I just apologize,” Thomas said. “I’m an adult. I’m a grown man, there’s absolutely no reason for me to say anything like that. It’s terrible….