GLOBAL MARKETS-Stocks fall on weak data, Syria air strikes

* European shares slump on fresh batch of downbeat data * Bond yields touch lowest in two weeks on safe-haven buys * Oil falls as Libyan, Iraqi output outweighs strikes on Syria (Adds close of European bond, stock markets) By Herbert Lash NEW YORK, Sept 23 (Reuters) - More downbeat data from Europe left global equity markets on course for a third day of losses on Tuesday, while U.S. air strikes in Syria set a cautionary tone and helped lift prices of safe-haven bonds. Pres