using System V 'cu'

[Guy Harris]

>The code for ~+ is #ifdef'ed in the HDB cu source. If you have HDB
>source, just remake cu with the appropriate -D option.

Unfortunately, many (quite possibly "most") people with HDB binaries do
not have HDB source....

The "#ifdef" symbol is "forfutureuse".  Eventually, "future" becomes
"present"; what is the event being waited for here?  Is there something
about it that doesn't work, or is somebody just chicken**** about
enabling it?