HIVE-5865 - AvroDeserializer incorrectly assumes keys to Maps will always be of type 'org.apache.avro.util.Utf8' (Ben Roling via Brock)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1629779 13f79535-47bb-0310-9956-ffa450edef68