Usage: int dds_wait4proc(int ms);
Returns: 0 if good status, -1 if bad status.
Argument: int ms
This routine waits until all processes attached to DD fifos are
sleeping on a semaphore (their fifo is empty).
It can be used to synchronize
the system, e.g. in a end run events after the trigger has been
disabled. Argument ms is a timeout value in millisec.