READ_ONLY FLAG IS SET

Problem:
In SBR, noop update query is logged into binlog even if the
read_only mode is set.

Analysis:
For noop update query, server itself identifies that there is
nothing to update. So this query doesn't go to SE and we don't mark
this statement trx as read_write.
As per the existing implementation for SBR, In case of
super_read_only mode, At the time of commit in "ha_commit_trans()"
if a read_write transaction is found, we are checking if this
transaction is coming from a handler other than binlog_handler. This
will ensure that there is a genuine read_write transaction being
sent by the engine apart from binlog_handler and only then it is
blocked.
For no operation UPDATE query, SE handler does not set statement
transaction as read-write. And if this transaction doesn't contains
any other genuine read_write statement transaction then at the time
of commit in "ha_commit_trans()", this transaction is considered as
non read-write transaction and it is not blocked.

Fix:
To make the binlogging consistent in read_only mode, Mark the
statement trx noop_read_write if it's not marked read_write in SE
handler. Then at the time of commit in "ha_commit_trans()", if the
transaction has noop read-write transaction then it is blocked.

Note:
In 8.0, it's impossible to set the super_read_only variable when a
transaction is active. So this fix is applicate only for 5.7.

RB: 21936
Reviewed by: Pedro Figueiredo <pedro.figueiredo@oracle.com>,
Bill Qu <bill.qu@oracle.com>