- two new MTR tests (appended to already existing suite/innodb/innodb_cats.test)
- added DBUG_EXECUTE_IF required to verify that trx->age is now well behaving in above tests
- change in RecLock::add_to_waitq, such that the lock_update_age is not called in case of DB_DEADLOCK
- removal of the redundant wait parameter of lock_update_age
- added C++11 [[ noreturn ]] attribute to ut_error,
- removed unreachable code after ut_error
- in particular removed the only use of DB_QUE_THR_SUSPENDED and thus simplified handling of lock_table
- adjusted @return doxygen comments to reflect that DB_QUE_THR_SUSPENDED is now an impossible value
- added some ut_ad asserts which verify that return value indeed matches the values advertised by @return documentation
- optimized lock_rec_add_to_queue by avoiding a search for similar lock, unless the type_mode permits reuse of a lock object
- fixed a comment for lock_prdt_lock to reflect that it can return DB_SUCCESS_LOCKED_REC

Reviewed-by: Jimmy Yang <jimmy.yang@oracle.com>
Reviewed-by: Marcin Babij <marcin.babij@oracle.com>