IS_USED_LOCK('lock') implementation


sql/item_create.cc:
  create_func_is_used_lock implementation
sql/item_create.h:
  create_func_is_used_lock declaration
sql/item_func.cc:
  thread_id member added to the ULL class
sql/item_func.h:
  class Item_func_is_used_lock added
sql/lex.h:
  IS_USED_LOCK function added to the SQL