fix: maximum receivable event size is INT_MAX.
fix: should release reference of sentry manually if one-shot event.
fix: should set EV_DELETE flag before calling lkq_sentry_unregister.
fix: do not need to use the bit64vec to confirm the sentry is registered.
change: bit64vec.h has been removed.
change: lkq_sentry_t structure has been changed.