Weigh-in final hurdle before Pacquiao-De la Hoya collision. One more thing before the welterweights collide. Get them to stand on the scales first, and see how heavy they are. Or for that matter, how heavy Manny Pacquiao is. And for Oscar de la Hoya, how lighter he has become. There will be no problems, however, during the weigh-in on Saturday (2 p.m. Friday, US time) at the MGM Grand Garden Arena, a formality really between two boxing superstars who expect something more earth-shaking to derail them…