Norman Mailer died nearly a decade ago, but the presence of the literary lion still looms large over this town, and certainly over the lives of his children. John Buffalo Mailer, who wrote the screenplay to “Blind,” which will show at the Provincetown International Film Festival, has often said that the Mailer clan were all required to be artists. That comes in handy when making collaborative art, such as this film starring Alec Baldwin and Demi Moore. Michael Mailer makes his directorial debut with “Blind” after decades of working as a producer.