Changing storage engine of ndb_binlog_index to use InnoDB.
This gives better behavior when purging logs where large parts of
the table can be deleted. Avoiding MyISAM table locking as well
as using InnoDB lock-free reads will give better availability.

Installation scripts mysql_system_tables.sql and mysql_system_tables_fix.sql
are updated to define/alter the ndb_binlog_index table to use InnoDB.

A new testcase ndb_binlog_purge_lock tests concurrent inserts
during purging of the binary logs (which deletes rows in ndb_binlog_index).
A new testcase ndb_binlog_purge_upgrade that first uses the mysql_upgrade
script and then checks ndb_binlog_purge_lock.
Updated ndb_rpl_circular to make scan order predictable.
Updated ndb_binlog_index.result since it checks table engine.