void silc_schedule_signal_call(SilcSchedule schedule, 
                                   SilcUInt32 signal);

    Mark the `signal' to be called later.  Every signal that has been
    registered by silc_schedule_signal_register is delivered by calling
    this function.  When signal really occurs, the application is 
    responsible of calling this function in the signal handler.  After
    signal is over the scheduler will then safely deliver the callback
    that was given to silc_schedule_signal_register function.