MXS-1530: check ANNOTATE_ROWS flag in connecting slave.
In MariaDB 10.2.4 replicate_annotate_row_events and
binlog_annotate_row_events have default to ON: this change checks
whether the connecting slave is not has ANNOTATE_ROWS in
blr_slave_binlog_dump(), those ANNOTATE_ROWS events can be sent or not
to the slave.