1) Fix so that scan takeover is possible after SR
2) Reserve two pages for SR "zero pages"


ndb/include/ndbapi/NdbOperation.hpp:
  remove unused method
ndb/src/kernel/blocks/dblqh/DblqhMain.cpp:
  Fix bug#4909
  don't reset tableFragptr during SR
ndb/src/kernel/blocks/dbtc/DbtcMain.cpp:
  Also send reason for disallowing rollback
ndb/src/kernel/blocks/dbtup/Dbtup.hpp:
  Add bitmask of free pages to use for page 0 during SR
ndb/src/kernel/blocks/dbtup/DbtupDebug.cpp:
  More prinout in unit test of PageMan
ndb/src/kernel/blocks/dbtup/DbtupPagMan.cpp:
  Reserve 2 pages to use for SR
ndb/src/kernel/blocks/dbtup/DbtupSystemRestart.cpp:
  Don't alloc using "normal" allocConsPages when allocating for
  0-pages during SR, instead use 2 reserved pages