GLOBAL MARKETS-Shares higher on year-end buying, ECB stimulus hints

* U.S. shares higher on year-end buying* ECB QE hopes, Greek political relief boost European shares* Gilead weighs on S&P, Nasdaq 100* Oil prices resume declines(Adds close of European stock markets, investor quote, updates prices)By Sam ForgioneNEW YORK, Dec 22 (Reuters) - Equity markets worldwide edged higher on Monday after rising expectations for more European stimulus supported shares in the