About 35 minutes into “If I Had Legs I’d Kick You,” an indie written and directed by Mary Bronstein, Rose Byrne’s Linda stretches out on her couch, stoned, and starts watching a schlocky horror movie in which suburban housewives feast on children. Linda asks Siri to identify the film (“What is movie…babies…zombies…’80s…mothers eating babies?”) and gets a chipper answer about Lindy Chamberlain, the Australian woman falsely convicted of killing her baby who was famously played by Meryl Streep in