STATUS'
NOTE: this is the backport to next-mr.
SHOW SHOW STATUS LIKE 'Slave_running' command believes that
if active_mi->slave_running != 0, then io thread is running normally.
But it isn't so in fact. When some errors happen to make io thread
try to reconnect master, then it will become transitional status
(MYSQL_SLAVE_RUN_NOT_CONNECT == 1), which also doesn't equal 0.
Yet, "SHOW SLAVE STATUS" believes that only if
active_mi->slave_running == MYSQL_SLAVE_RUN_CONNECT, then io thread is running.
So "SHOW SLAVE STATUS" can get the correct result.
Fixed to make SHOW SHOW STATUS LIKE 'Slave_running' command have the same
check condition with "SHOW SLAVE STATUS". It only believe that the io thread
is running when active_mi->slave_running == MYSQL_SLAVE_RUN_CONNECT.
This patch adds functionality to row-based replication to ensure the
slave's column sizes are >= to that of the master.
It also includes some refactoring for the code from WL#3228.
