This turned out to be a problem for prepared statements as well; the id was
evaluated once, at parse time.


mysql-test/r/auto_increment.result:
  Updated results after bugfix in last_insert_id().
mysql-test/r/query_cache.result:
  Updated results after bugfix in last_insert_id().
mysql-test/r/variables.result:
  Updated results after bugfix in last_insert_id().
sql/item_func.cc:
  Fixed bug in last_insert_id(); get id at each evaluation (and not in the parser).
  Renamed the class Item_func_set_last_insert_id too, since it's not only for setting.
sql/item_func.h:
  Fixed bug in last_insert_id(); get id at each evaluation (and not in the parser).
  Renamed the class Item_func_set_last_insert_id too, since it's not only for setting.
sql/sql_yacc.yy:
  Fixed bug in last_insert_id(); get id at each evaluation (and not in the parser).
  Renamed the class Item_func_set_last_insert_id too, since it's not only for setting.
tests/client_test.c:
  Test case for last_insert_id() in prepared statements.