HIVE-8517: When joining on partition column NDV gets overridden by StatsUtils.getColStatisticsFromExpression (Mostafa Mokhtar, reviewed by Prasanth J)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1634004 13f79535-47bb-0310-9956-ffa450edef68