This 90-minute biography, literary and otherwise, of Philip Roth is unusual for American Masters, in that the subject dominates the interview portions of the documentary. There are a handful of other voices speaking briefly, but this is mostly Roth himself, speaking about his inspirations, his career, and so much else. And it’s a charming and spellbinding way to go, especially when you realize that Roth, so glib and funny and honest, almost never made any talk-show rounds during his long,