IMPALA-1177: The AntiJoin code was not resetting correctly the hash table iterator

The AntiJoin code path was not resetting the hash table iterator when it was finding
a match for the current row. As a result the hash table iterator was pointing to the
wrong row when EvalConjuncts was being called.

Change-Id: I37bc457ccf999755f7f76ee30b24c5a12cb10a19
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/4215
Reviewed-by: Ippokratis Pandis <ipandis@cloudera.com>
Tested-by: jenkins