New prototype for get_auto_increment() (but new arguments not yet used), to be able
to reserve a finite interval of auto_increment values from cooperating engines.
A hint on how many values to reserve is found in handler::estimation_rows_to_insert,
filled by ha_start_bulk_insert(), new wrapper around start_bulk_insert().
NOTE: this patch changes nothing, for all engines. But it makes the API ready for those
engines which will want to do reservation.
More csets will come to complete WL#3146.


sql/ha_berkeley.cc:
  update to new prototype of get_auto_increment
sql/ha_berkeley.h:
  update to new prototype of get_auto_increment
sql/ha_heap.cc:
  update to new prototype of get_auto_increment
sql/ha_heap.h:
  update to new prototype of get_auto_increment
sql/ha_innodb.cc:
  update to new prototype of get_auto_increment
sql/ha_innodb.h:
  update to new prototype of get_auto_increment
sql/ha_myisam.cc:
  update to new prototype of get_auto_increment
sql/ha_myisam.h:
  update to new prototype of get_auto_increment
sql/ha_ndbcluster.cc:
  update to new prototype of get_auto_increment
sql/ha_ndbcluster.h:
  update to new prototype of get_auto_increment
sql/ha_partition.cc:
  update to new prototype of get_auto_increment
sql/ha_partition.h:
  update to new prototype of get_auto_increment
sql/handler.cc:
  new prototype of get_auto_increment, comments, preparation for when the MySQL layer is capable
  of getting finite auto_increment intervals from cooperating engines.
sql/handler.h:
  a wrapper around start_bulk_insert(): ha_bulk_insert(), which stores the argument (number
  of rows expected for insertion) into a member of handler: estimation_rows_to_insert.
  This member will soon be used to decide how much auto_increment values we want to reserve
  from cooperating engines.
  New prototype for get_auto_increment, preparing for cooperating engines to reserve finite auto_increment
  intervals.
  release_auto_increment() will be used by the MySQL layer to inform the engine that it has
  not used all of the interval (engine can reclaim it).
sql/log.cc:
  note for the future
sql/log_event.cc:
  name of wrapper
sql/sql_insert.cc:
  name of wrapper. When done with inserting, return unused auto_inc values to engine.
sql/sql_load.cc:
  name of wrapper. When done with inserting, return unused auto_inc values to engine.
sql/sql_select.cc:
  name of wrapper
sql/sql_table.cc:
  name of wrapper
storage/archive/ha_archive.cc:
  update to new prototype of get_auto_increment.
  Archive reserves only one value (Archive's god - Brian - told me that's the truth).
storage/archive/ha_archive.h:
  update to new prototype of get_auto_increment()