HOYLAKE, England — Rory McIlroy looks as if he had just thrown a knockout punch at the British Open, and it was only Saturday. When he rolled in a 10-foot eagle putt on the final hole for a 4-under 68, he straightened his back, stared defiantly at thousands of fans crammed into the horseshoe arena around the 18th green at Royal Liverpool and lightly pumped his fist. He went from being tied for the lead to six shots ahead of Rickie Fowler in just over an hour.