Jon Burlingame editorOscar winner Rachel Portman (“Emma”) served up a delightful score for “Julia,” the documentary about cooking personality Julia Child from “RBG” filmmakers Betsy West and Julie Cohen.Curiously, the English composer had never seen Child’s public TV series “The French Chef” and, although she loves to cook, does not own Child’s classic book “Mastering the Art of French Cooking.”Portman, who recently received a lifetime achievement award from Germany’s SoundTrack Cologne, spoke