What’s left to say about “The Godfather"? Upon the film’s release in 1972, it almost instantly became a byword for the best Hollywood has to offer. It minted a new generation of stars, earned hundreds of millions of dollars, established Francis Ford Coppola as one of the best directors of his generation, and changed the way Americans viewed the mafia—and cinema—forever.    And yet, “The Godfather” almost never got made, with meddling studio executives and vindictive members of the real-life mafia trying to smother the movie at every turn. During production, location permits were revoked, war was waged over casting decisions, author Mario Puzo got into a public brawl with Frank Sinatra, a producer’s car was riddled with bullets, and “connected” men auditioned for—and in some cases landed—parts in the film.    On “Leave the Gun, Take the Cannoli,” Mark Seal, author of the 2021 book by the same title, and Nathan King, a deputy editor of AIR MAIL, present new and archival interviews with Coppola, James Caan, Robert Evans, Talia Shire, Al Ruddy, and many others, stripping back the varnish of movie history to reveal the complicated genesis of a modern masterpiece.