By Emma Farge GENEVA (Reuters) – Western states should enact policies to prevent asylum seekers embarking on dangerous routes, the U.N. refugee chief said on Thursday, as the number of migrants through the Darien Gap this year tops half a million people. Conflicts, poverty and climate change have driven a record 114 million people from their homes around the world while Western governments are under growing domestic pressure to get tougher on asylum seekers, with some considering schemes to deport them. The Darien Gap, a notorious stretch of jungle in Panama, has become a treacherous part of t…