trx_t::will_lock: Changed the type to bool.

trx_t::is_autocommit_non_locking(): Replaces
trx_is_autocommit_non_locking().

trx_is_ac_nl_ro(): Remove (replaced with equivalent assertion expressions).

assert_trx_nonlocking_or_in_list(): Remove.
Replaced with at least as strict checks in each place.

check_trx_state(): Moved to a static function; partially replaced with
individual debug assertions implementing equivalent or stricter checks.

This is a backport of commit 7b51d11c
from 10.5.