“The Inner Life of Martin Frost” begins with a slow tracking shot of family photographs belonging to Jack and Diane Restau, the owners of the country house to which author Martin Frost has escaped having just finished a novel. But upon closer inspection, one recognizes that these are pictures of Paul Auster, the film’s writer and director, and his wife, the author Siri Hustvedt. (Rearrange the letters of the surname Restau, and it becomes Auster).