(Reuters) - Democratic presidential candidates Hillary Clinton and Bernie Sanders on Wednesday cheered the end of U.S. drugmaker Pfizer Inc’s (PFE.N) $160 billion merger with Ireland-based Allergan Plc (AGN.N). “Glad to hear Pfizer is calling off the merger. We need to close the loopholes that let corporations escape paying their taxes,” Clinton said on Twitter.  Sanders said on the social media site that he applauded President Barack Obama for new rules aimed at curbing so-called inversion deals, which Pfizer said led it to scrap the deal. 