In the tradition of “Percepto” and “Odorama,” director Gary Hustwit’s “Eno” comes with a gimmick. Granted, it’s unlike that used for William Castle’s “The Tingler” (1959), wherein buzzers were applied to selected seats in movie theaters in order to simulate the sensation caused by the title monster. Nor is it like the scratch-and-sniff card that accompanied John Waters’s “Polyester” (1981), a cinematic aid meant to embellish the film’s mise en scène. Mr. Hustwit’s gimmick is less kitschy but just as conducive to the film’s subject.