HIVE-4820 : webhcat_config.sh should set default values for HIVE_HOME and HCAT_PREFIX that work with default build tree structure (Eugene Koifman via Jianyong Dai)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1503940 13f79535-47bb-0310-9956-ffa450edef68