Method wait_until

src/bthread/condition_variable.h:92–97

    }

    int wait_until(std::unique_lock<bthread::Mutex>& lock,
                   timespec duetime) {
        const int rc = bthread_cond_timedwait(
                &_cond, lock.mutex()->native_handler(), &duetime);
        return rc == ETIMEDOUT ? ETIMEDOUT : 0;
    }

    int wait_until(std::unique_lock<bthread_mutex_t>& lock,
                   timespec duetime) {