ndb/include/kernel/signaldata/AlterTable.hpp:
  Add error code for backup in progress
ndb/include/kernel/signaldata/DictTabInfo.hpp:
  Add backup state
ndb/include/kernel/signaldata/DropTable.hpp:
  Add error code for backup in progress
ndb/include/ndbapi/NdbDictionary.hpp:
  Add backup state
ndb/src/kernel/blocks/backup/Backup.cpp:
  1) remove invalid require (util_sequence_ref) crash
  2) Don't backup objects dropping/creating
  3) set correct error code on backup fragment ref (crash)
  4) save TrigAttrInfo header when getting log full (crash)
  5) lock/unlock tables during backup
ndb/src/kernel/blocks/dbdict/Dbdict.cpp:
  1) add mutex lock/unlock as part of drop/alter table
  2) add lock/unlock for backup
  3) remove TC from backup trigger loop
ndb/src/kernel/blocks/dbdict/Dbdict.hpp:
  Add BACKUP_ONGOING state
ndb/src/ndbapi/NdbDictionaryImpl.cpp:
  Add backup state
ndb/src/ndbapi/ndberror.c:
  Add error code for backup in progress
ndb/test/ndbapi/testBackup.cpp:
  Add testcase for testBackup -n BackupDDL
ndb/tools/drop_index.cpp:
  Fix ndb_drop_index
ndb/tools/listTables.cpp:
  Print of backup state