on subquery inside a SP 

Problem: repeated call of a SP containing an incorrect query with a 
subselect may lead to failed ASSERT().

Fix: set proper sublelect's state in case of error occured during 
subquery transformation.


mysql-test/r/sp.result:
  Fix for bug#46629: Item_in_subselect::val_int(): Assertion `0' 
  on subquery inside a SP 
    - test result.
mysql-test/t/sp.test:
  Fix for bug#46629: Item_in_subselect::val_int(): Assertion `0' 
  on subquery inside a SP 
    - test case.
sql/item_subselect.cc:
  Fix for bug#46629: Item_in_subselect::val_int(): Assertion `0' 
  on subquery inside a SP 
    - don't set Item_subselect::changed in the Item_subselect::fix_fields()
  if an error occured during subquery transformation.
  That prevents us of further processing incorrect subqueries after 
  Item_in_subselect::select_in_like_transformer().