NEW YORK, March 31 : Technology shares are struggling to act as safe havens in the turbulence wrought by the Iran conflict - and that could be a big problem for the broader U.S. stock market. Tech and other megacap tech-related stocks have led U.S. equity indexes higher during much of a bull run that has lasted more than three years, with investors flocking to these massive companies known for their strong earnings, solid balance sheets and competitive business advantages. But the group, which