Fixing bug where UPDATE failed on slave and some cleanup of ndb_unpack_record().


mysql-test/r/rpl_bit_npk.result:
  Result change
mysql-test/t/disabled.def:
  Disabling tests
mysql-test/t/rpl_bit_npk.test:
  Making test storage-engine independent
mysql-test/t/rpl_ndb_innodb2ndb-slave.opt:
  Storage engine name change
mysql-test/t/rpl_ndb_myisam2ndb-slave.opt:
  Storage engine name change
sql/ha_ndbcluster.cc:
  Using move_field_offset() to move field pointer.
  Using my_ptrdiff_t instead of uint for pointer difference.
  Removing ineffective cast.
  Calling member function directly, bypassing the virtual mechanism
  for Field_bit.
sql/log_event.cc:
  Starting and stopping range scan and index read inside find_and_fetch row
  instead of in calling function. There are storage engines that require the
  search to be restarted for every changed row.