- invalidate ndb dict cache on cluster disconnect (ClusterMgr.cpp)
- add check for correct frm on external lock when table cache is found invalid


ndb/include/ndbapi/ndb_cluster_connection.hpp:
  Bug #16875 Using stale MySQLD FRM files can cause restored cluster to fail
ndb/src/ndbapi/ClusterMgr.cpp:
  Bug #16875 Using stale MySQLD FRM files can cause restored cluster to fail
ndb/src/ndbapi/ClusterMgr.hpp:
  Bug #16875 Using stale MySQLD FRM files can cause restored cluster to fail
ndb/src/ndbapi/DictCache.cpp:
  Bug #16875 Using stale MySQLD FRM files can cause restored cluster to fail
ndb/src/ndbapi/DictCache.hpp:
  Bug #16875 Using stale MySQLD FRM files can cause restored cluster to fail
ndb/src/ndbapi/TransporterFacade.hpp:
  Bug #16875 Using stale MySQLD FRM files can cause restored cluster to fail
ndb/src/ndbapi/ndb_cluster_connection.cpp:
  Bug #16875 Using stale MySQLD FRM files can cause restored cluster to fail
ndb/src/ndbapi/ndb_cluster_connection_impl.hpp:
  Bug #16875 Using stale MySQLD FRM files can cause restored cluster to fail
sql/ha_ndbcluster.cc:
  Bug #16875 Using stale MySQLD FRM files can cause restored cluster to fail
mysql-test/r/ndb_autodiscover3.result:
  Bug #16875 Using stale MySQLD FRM files can cause restored cluster to fail
mysql-test/t/ndb_autodiscover3.test:
  Bug #16875 Using stale MySQLD FRM files can cause restored cluster to fail