If server has not been initialized as a slave (by CHANGE MASTER), then
SHOW SLAVE STATUS will return an empty set, and caused the waiting for
Slave_IO_running or Slave_SQL_running to 'No' fail.

This patch fixed the problem by return immediately if slave is not
initialized in include/wait_for_slave_*_to_stop.inc.


mysql-test/include/wait_for_slave_io_to_stop.inc:
  Return immediately if slave is not initialized
mysql-test/include/wait_for_slave_sql_to_stop.inc:
  Return immediately if slave is not initialized
mysql-test/include/wait_for_slave_to_stop.inc:
  Return immediately if slave is not initialized