By Mark Lamport-Stokes OAKMONT, Pennsylvania, June 14 (Reuters) - Concerns over the Zika virus at the 2016 Rio Games have been a hot topic of conversation among the golfers at this week's U.S. Open, with many of them opting to play a waiting game until August. Earlier this month, world number one Jason Day expressed doubts for the first time over whether he would compete at the Summer Olympics in Brazil while third-ranked Rory McIlroy on Tuesday said his focus, for the moment, was on golf's majors. "It's still a good bit away," Northern Irishman McIlroy told reporters at Oakmont Country Club about the Aug. 5-21 Rio Olympics. More...