GLOBAL MARKETS-European shares fall as bank stress test worries offset ECB stimulus talk

* Efe says at least 11 banks to fail EU stress tests* Sources say ECB considering buying corporate bonds* Earnings results beat expectations in Europe, the U.S.(Recasts)By Marius ZahariaLONDON, Oct 22 (Reuters) - European shares slipped and the euro hit a one-week low on Wednesday as reports that at least 11 banks could fail a region-wide financial health check this weekend offset hopes of corpora