When a foreign key is added or dropped as a part of any DDL, all the
parent tables referenced by the foreign key should be flushed out of
the server cache to force reload the FK metadata in the handler. This is
already done by the fix for Bug#24666177. When this DDL is distributed
to other mysqlds connected to the same cluster, the same is not being
done as a part of schema distribution. Due to this any subsequent
queries relying on the foreign key metadata information of the
corresponding parent tables might return inconsistent results.

Fix for versions 7.5 & 7.6:
When the DDL query is distributed and reaches the participant mysqld,
any previous foreign key information is already lost. Since the server
doesn't have any information about the foreign keys and the
NdbDictionary has already dropped the foreign key, there is no way to
retrieve the foreign keys and the tables being referenced by them.
So, the fix is to make ndb_binlog flush out all the tables caches in
server whenever the ndb_binlog encounters a DDL that might have
added/dropped a foreign key.