CAPE CANAVERAL, Fla. — Astronauts kept busy fixing and hauling gear aboard the linked Atlantis and International Space Station on Saturday, as the last shuttle flight drew closer to an end. Atlantis’ pilots got a jammed storage locker open and retrieved air purifiers for the space station. In more good news, they brought back online a computer that abruptly stopped working two days earlier, the second computer failure in five days aboard Atlantis.