Here’s something you don’t see every day: A Hollywood director walking a goat on the beach. But there was Doug Liman, director of “The Bourne Identity” and “Mr. and Mrs. Smith,” walking his pet goat along the shore in Aquinnah on Martha’s Vineyard. Liman’s next film is “All You Need Is Kill,” a sci-fi/action flick starring Tom Cruise and Emily Blunt. No ordinary goat, Liman’s pet — named Ruby — won a blue ribbon at last summer’s Martha’s Vineyard Agricultural Fair.