using System V 'cu'

[Guy Harris]

>My guess is that it is a standards issue: they're waiting for code
>merger with SUN/BSD, and the analogous option in "tip" is called
>something else.

Unlikely:

	1) S5R3 antedates the AT&T/Sun agreement, and the #ifdef in
	   question is in S5R3 (and may be in earlier releases);

	2) the BSD "tip" has a "cu mode" wherein it emulates V7's "cu",
	   so if the two are merged into one utility (as opposed to just
	   leaving them as two separate programs), it could use
	   different options in different modes.