A gunman fired off at least three rounds in front of an NYC Housing Authority building in Harlem, law-enforcement officials said Saturday. One of the bullets pierced an unoccupied Toyota Camry at about 10:30 p.m. on June 26, cops said. Just before the gunfire, a group of men argued behind the building at 1909 Amsterdam Ave., police said. It’s unclear if the shooter, who tossed the gun and fled, was involved in that dispute. Police recovered a .22-caliber semiautomatic pistol, along with three spent shells.