DML transactions on FK-child tables also get table locks
on FK-parent tables. If there is a DML transaction holding
such a lock, and a TOI transaction starts, the latter
BF-aborts the former and puts itself into a waiting state.
If at this moment another DML transaction on FK-child table
starts, it doesn't check that the transaction waiting on
a parent table lock is TOI, and it erroneously BF-aborts
the waiting TOI transaction.

The fix: don't roll back high-priority transaction waiting
on a lock in InnoDB, instead roll back an incoming DML
transaction.
Signed-off-by: Julius Goryavsky <julius.goryavsky@mariadb.com>