fix so that getElement read localkey from lockowner instead of from page
  plus some cleanups


storage/ndb/src/kernel/blocks/dbacc/DbaccMain.cpp:
  1) Use OP_INITIAL instead of ~0
  2) Use JBB instead of JBA (once that I temporary changed...)
  3) Add more validation to validate_lock_queue (insert/delete)
  4) make getElement read localkey from lockowner instead of from page