HIVE-7616 : pre-size mapjoin hashtable based on statistics (Sergey Shelukhin, reviewed by Gunther Hagleitner, Prasanth J, Mostafa Mokhtar, Gopal V)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1617399 13f79535-47bb-0310-9956-ffa450edef68