GLOBAL MARKETS-Stocks, dollar dip as Fed to start meeting

* Asian, European shares trim recent lofty gains * Dollar hovers above four-week low * Oil extend drop as Syrian tensions further ease By Blaise Robinson PARIS, Sept 17 (Reuters) - Shares dipped and the dollar lost ground on Tuesday as investors consolidated positions before a U.S. Federal policy meeting at which the central bank is set to start scaling back stimulus. German Bunds also edged lower, with the 10-year yields rising 1 basis point to 1.888 percent. The FTSE