SOUTHPORT, England — Jordan Spieth expected a rough time at the British Open before he even got to the golf course. He spent Friday morning at his rented house in front of the television, watching players battle a relentless wind at Royal Birkdale, all the while checking a forecast that was even worse for when he played in the afternoon. “It wasn’t a great feeling knowing we were coming into something harder than what we were watching,” he said. Spieth did more than just survive. With a short game as sharp as it has been all year, and a 3-wood that turned out a lot better than it looked and led to an eagle, Spieth seized control with a 1-under 69 that gave him a two-shot lead over Matt Kuchar going into the weekend. Spieth turned a bogey or worse into an unlikely par by chipping in from just short of the 10th green.