Bug#40142: possible reason of timeout is stopped slave threads before

sync_with_master command. The patch add waiting of proper state of slave 
before sync with master.

mysql-test/suite/rpl/t/rpl_start_stop_slave.test

@@ -25,6 +25,7 @@ let $wait_condition= SELECT COUNT(*) > 0 FROM t1;
 source include/wait_condition.inc;
 stop slave io_thread;
 start slave io_thread;
+source include/wait_for_slave_to_start.inc;
 sync_with_master;
 
 connection master;