Fix bug #2167: generate foreign key id's locally for each table, in the form databasename/tablename_ibfk_number; if the user gives the constraint name explicitly remember it; these changes should ensure that foreign key id's in a slave are the same as in the master, and DROP FOREIGN KEY does not break replication
sync0sync.c:
  UNIV_SYNC_DEBUG caused assertion in the creation of the doublewrite buffer, if we do not allow thousands of latches per thread