Sam Peckinpah’s “Straw Dogs,” released forty years ago, is perhaps the most thematically confused thriller ever made. On the surface, it’s a standard fish-out-of-water/revenge story: a stuffy professor, David (Dustin Hoffman) and his lithe, blonde, British housewife Amy (Susan George) are tormented by hooligans—including Amy’s ex-boyfriend—when they move back to her rustic England hometown. At first, these roughnecks, who