avoiding of calling Item::val_* methods family with opt_range mem_root, because its life time is too short. (BUG#14342)


mysql-test/r/subselect_innodb.result:
  BUG#14342 test case
mysql-test/t/subselect_innodb.test:
  BUG#14342 test case
sql/opt_range.cc:
  avoiding of calling Item::val_* methods family with opt_range mem_root, because its life time is too short.