Backport WL#5917 sufficient to be able to replicate row events from mysql 5.6 master with default options

MySQL 5.6 has WL#5917, which introduces new binlog events for row-based
replication, enabled by default.

These new events are unknown by earlier slave servers, so replication from
MySQL server 5.6.7 to current MariaDB 10.0.0 fails on the first row event with
errno 1594 (Relay log read failure: Could not parse relay log event entry).

MySQL 5.5 slave is similarly affected.

There is an option --log-bin-use-v1-row-events which can be enabled on the
master, thereby using the old event format for row events and allowing
replication to MariaDB 10.0 slave to work.

However, it would be good to backport the new row event format to MariaDB
10.0, so it could work as a slave against MySQL 5.6 masters with default
configuration.

The commit comment for WL#5917 reads like the new row format is mostly to be
able to include some extra information used by NDB cluster, so it may be that
backporting could be as easy as ignoring any extra information when reading
events from the master.

To reproduce:

# Start servers with default parameters, plus server-ids and log-bin on MySQL 5.6.7 (to be a master)

# Start replication MySQL 5.6.7 => MariaDB 10.0.0

# On MySQL 5.6.7 (master) 

set binlog_format=row;

create table t1 (i int);

insert into t1 values (1);

# On MariaDB 10.0.0 (slave) observe replication failure

bzr branch 10.0-serg

revision-id: wlad@montyprogram.com-20121029155215-6neh71dtrxywpyeb

date: 2012-10-29 16:52:15 +0100

revno: 3463