Rewrite NOT IN subqueries with a null-aware anti-join.

This commit fixes the issue (IMPALA-1215) where NOT IN subqueries return
wrong results in the presence of NULL values. The null-matching equality
operator is introduced in the front-end and the NOT IN subqueries are
rewritten using the null-aware anti-join operator.

Change-Id: I5a323357025d77c2143db86e1057999ec8a371c0
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/4391
Reviewed-by: Dimitris Tsirogiannis <dtsirogiannis@cloudera.com>
Tested-by: jenkins
Fix code coverage build due to analytic tests w/ NULLs failing on HBase

Change-Id: I2aab2ca8a5c5c3bfa3bd1572c3d24644dde2792a
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/4437
Reviewed-by: Alex Behm <alex.behm@cloudera.com>
Tested-by: jenkins
Fix decimal mod overflow check.

Change-Id: Ieb74cf05e491078a7acc2ac118587fdaef3f38a6
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/4435
Reviewed-by: Alex Behm <alex.behm@cloudera.com>
Tested-by: jenkins
IMPALA-1282: Identical select-list aliases pointing to the same expr are not ambiguous.

Change-Id: If2d395620b1a077d128987b3d139fb5ef1b95e30
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/4434
Reviewed-by: Alex Behm <alex.behm@cloudera.com>
Tested-by: jenkins