If threads are not present, this routine has no effect.

    This routine adds a specified interval to the current absolute
    system time and returns a new absolute time. This new absolute
    time is used as the expiration time in a call to tis_cond_
    timedwait().

    The timespec structure contains the following two fields:

    o  tv_sec is an integral number of seconds.

    o  tv_nsec is an integral number of nanoseconds.