mysql-test/r/ps.result:
  New test case for BUG#3486.
mysql-test/t/ps.test:
  New test case for BUG#3486.
sql/item_create.cc:
  Create an Item_func_found_rows() at parse time, not an Item_int.
sql/item_func.cc:
  Added val_int() method for new Item_func_found_rows class.
sql/item_func.h:
  New class Item_func_found_rows for FOUND_ROWS() function.
sql/sql_select.cc:
  Don't reset thd->limit_found_rows too early, or FOUND_ROWS() wont work.