As if the Hollywood’s Box-Office numbers this summer couldn’t get any worse comes the news that the slumping sequels of the last few months can add two more casualties: Sony’s “MIB: International” and Warner Bros.’ “Shaft.” Both are set to open way below tracker expectations and will consequentially join other Summer box-office bombs such as “Dark Phoenix” “The Secret Life of Pets 2” “Rocketman" and “Godzilla,”