this also impl. gcp safe multi node shutdown
  1) block gcp
  2) wait for ongoing gcp
  3) inform all stopping QMGR's (so that they don't start with error handler)
  4) wait for all QMGR's to reply
  5) broadcast failrep for stopping nodes
  6) (if !master died) unblock gcp

  


ndb/include/kernel/signaldata/DumpStateOrd.hpp:
  Impl. GCP safe multi node shutdown in order to test bug#18612
ndb/include/kernel/signaldata/FailRep.hpp:
  Impl. GCP safe multi node shutdown in order to test bug#18612
ndb/include/kernel/signaldata/StopReq.hpp:
  Impl. GCP safe multi node shutdown in order to test bug#18612
ndb/src/kernel/blocks/ndbcntr/Ndbcntr.hpp:
  Impl. GCP safe multi node shutdown in order to test bug#18612
ndb/src/kernel/blocks/ndbcntr/NdbcntrInit.cpp:
  Impl. GCP safe multi node shutdown in order to test bug#18612
ndb/src/kernel/blocks/ndbcntr/NdbcntrMain.cpp:
  Impl. GCP safe multi node shutdown in order to test bug#18612
ndb/src/kernel/blocks/qmgr/Qmgr.hpp:
  Impl. GCP safe multi node shutdown in order to test bug#18612
ndb/src/kernel/blocks/qmgr/QmgrInit.cpp:
  Impl. GCP safe multi node shutdown in order to test bug#18612
ndb/src/kernel/blocks/qmgr/QmgrMain.cpp:
  Impl. GCP safe multi node shutdown in order to test bug#18612
ndb/test/ndbapi/testNodeRestart.cpp:
  test program for bug#18612