Make sure that the Annotate_rows_log_events is written into
binlog only for the first fragment of the current statement.
Also avoid flusing pending rows event when calculating bytes
generated by the transaction.

Added and recorded a test which verifies that the binlog
contains only one Annotate_rows_log_event per statement
with various SR settings. Recrded mysql-wsrep-features#136
which produced different output with excession log events
suppressed.