Fix for valgrind warning/crashes: When executing SP statement, If we set  thd->user_var_events_alloc (and so get binlog events to be allocated on its pool),  clean the binlog events after the execution of this SP statement is finished.
Fix for valgrind warning/crashes: When executing SP statement, If we set 
thd->user_var_events_alloc (and so get binlog events to be allocated on its pool), 
clean the binlog events after the execution of this SP statement is finished.

natsys/mariadb_10.2,natsys/mariadb_10.2,flynn1973/mariadb-aix,natsys/mariadb_10.2,flynn1973/mariadb-aix,flynn1973/mariadb-aix,davidl-zend/zenddbi,davidl-zend/zenddbi,davidl-zend/zenddbi,flynn1973/mariadb-aix,flynn1973/mariadb-aix,davidl-zend/zenddbi,davidl-zend/zenddbi,ollie314/server,davidl-zend/zenddbi,davidl-zend/zenddbi,ollie314/server,natsys/mariadb_10.2,natsys/mariadb_10.2,ollie314/server,davidl-zend/zenddbi,flynn1973/mariadb-aix,natsys/mariadb_10.2,natsys/mariadb_10.2,davidl-zend/zenddbi,ollie314/server,flynn1973/mariadb-aix,natsys/mariadb_10.2,flynn1973/mariadb-aix,ollie314/server,ollie314/server,ollie314/server,flynn1973/mariadb-aix,davidl-zend/zenddbi,flynn1973/mariadb-aix,slanterns/server,natsys/mariadb_10.2,ollie314/server,davidl-zend/zenddbi,natsys/mariadb_10.2,ollie314/server,ollie314/server,flynn1973/mariadb-aix,natsys/mariadb_10.2,ollie314/server