use of first_batch_size


ndb/include/kernel/ndb_limits.h:
  New maximum size
ndb/include/kernel/signaldata/ScanFrag.hpp:
  New error code
ndb/include/kernel/signaldata/ScanTab.hpp:
  Need to go to Uint16 when batch size > 255
ndb/src/kernel/blocks/dblqh/Dblqh.hpp:
  Uint8 => Uint16 when batch_size > 255
  New and changed methods for acc ptr's and
  checking end of scan batch (incl. check of batch_byte_size
ndb/src/kernel/blocks/dblqh/DblqhMain.cpp:
  Uint8 => Uint16 when batch_size > 255
  New and changed methods for acc ptr's and
  checking end of scan batch (incl. check of batch_byte_size