In MDEV-515, we enabled an optimization where an insert into an
empty table will use table-level locking and undo logging.
This may break applications that expect row-level locking.

The SQL statements created by the mysqldump utility will include the
following:

    SET unique_checks=0, foreign_key_checks=0;

We will use these flags to enable the table-level locked and logged
insert. Unless the parameters are set, INSERT will be executed in
the old way, with row-level undo logging and implicit record locks.