(SCRUM)
counters was not moved to SELECT_LEX because it used in methods inherited from select_result which should be applied to whole union results


mysql-test/r/union.result:
  this is results is true
sql/item_subselect.cc:
  limit initialization moved to method of SELECT_LEX_UNIT
sql/sql_derived.cc:
  limit initialization moved to method of SELECT_LEX_UNIT
sql/sql_lex.cc:
  limit initialization moved to method of SELECT_LEX_UNIT
sql/sql_lex.h:
  limit initialization moved to method of SELECT_LEX_UNIT
sql/sql_parse.cc:
  limit initialization moved to handle_select for single select (UNIONs already have it)
sql/sql_select.cc:
  limit initialization moved to method of SELECT_LEX_UNIT
sql/sql_union.cc:
  layout fixed
  limit initialization moved to method of SELECT_LEX_UNIT