part 2 - handle safecounter.init() failing in all parts of event code


storage/ndb/src/kernel/blocks/dbdict/Dbdict.cpp:
  Handle out safecounter.init() failing
storage/ndb/src/kernel/blocks/suma/Suma.cpp:
  Dont try to get table RNIL
storage/ndb/test/ndbapi/test_event.cpp:
  Add testcase for subscribe/unscubscribe