Anyone interested in playing six degrees of separation would have had a field day at this year’s Director Roundtable — and not just because half of the helmers made their films for Netflix. Martin Scorsese (The Irishman), 77, came this close to producing Joker from Todd Phillips, 48, only to pull out and leave it in the hands of his producing partner, Emma Tillinger Koskoff. His last movie, Silence, screened for Pope Francis I, the subject of The Two Popes by Fernando Meirelles, 64. And he’s been longtime friends with Steven Spielberg, who gave Greta Gerwig, 36, notes on her new drama, Little Women. Gerwig, of course, is life partners with Noah Baumbach (Marriage Story), 50, and in case you’re thinking Lulu Wang (The Farewell), 36, may have felt left…