KIAWAH ISLAND, South Carolina (Reuters) - Rory McIlroy brushed aside any lingering doubts over his ability to be a dominant force in golf by storming to a second major title with a stunning eight-shot victory at the PGA Championship on Sunday. McIlroy's first big triumph, a similar eight-shot victory at last year's U.S. Open, was followed by a series of poor showings in the majors, including a ...