BUG#47749: rpl_slave_skip fails sporadically on PB2 (mysql-5.1-rep+2 tree).
BUG#47749: rpl_slave_skip fails sporadically on PB2 (mysql-5.1-rep+2 tree).

rpl_slave_skip fails randomly on PB2. This patch fixes the failure by
setting explicit wait for SQL thread to stop, instead of the 
wait_for_slave_to_stop mysqltest command, after a start until command 
is executed.

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