IN DIFF_TABLES.INC

Problem
-------

The MTR test rpl_gtid.rpl_gtid_temp_table fails sporadically on
pushbuild on perpush as well as weekly/daily runs due to diff-
erence in table contents between master and slave being reported
by "include/diff_tables.inc".

Analysis
--------

The issue seems to be caused because of missing synchronization point
between master and slave after the workload and before the master/slave
diff tables check.

Fix
---

Added a master/slave synchronization before table diff checks.