Fix bug in lcp during drop table
  Make sure that file thread is not started until meta data has completed


storage/ndb/src/kernel/blocks/backup/Backup.cpp:
  Fix bug in lcp during drop table
  Make sure that file thread is not started until meta data has completed
storage/ndb/src/kernel/blocks/backup/Backup.hpp:
  Fix bug in lcp during drop table
  Make sure that file thread is not started until meta data has completed
storage/ndb/src/kernel/blocks/backup/FsBuffer.hpp:
  Fix bug in lcp during drop table
  Make sure that file thread is not started until meta data has completed