J.B. Holmes hung on to shoot a 2-under 68 and take a one-stroke lead into the clubhouse midway through the second round of the PGA Championship on Friday. Out on the course, first-round co-leader Jeev Milkha Singh was at 2 under early in his round. While Holmes, who spurted to the outright lead with three consecutive birdies on the back nine, was the only player to finish the second round below par,...