Wild vi diagnostic after "stty susp ^@" under 4.[12] (with fix)-REPOST

[Arthur David Olson]

Bugee--
	/usr/src/cmd/ex/ex_tty.c	on 4.1bsd
	/usr/src/ucb/ex/ex_tty.c	on 4.2bsd
	/and/may/be/a/bug		on 2.?bsd

Bug--
	The programs "vi" and "ex" produce a spurious "Missing lhs" diagnostic
	if run after you have issued a
		stty susp ^@
	command.

Repeat by--
	stty susp ^@
	ex

Partial cure--
	This "cure" gets rid of the spurious diagnostic.
	Alas, when the user tries to suspend their job by typing ^@,
	"vi" and "ex" will proceed to beep at them.  Any ideas?

	ed /usr/src/cmd/ex/ex_tty.c
	/ldisc == NTTYDISC/i
	#ifdef OLDVERSION
	.
	/ldisc == NTTYDISC/a
	#else
			if (ldisc == NTTYDISC && olttyc.t_suspc != '\0') {
	#endif
	.
	w
	q

Bugout--
	I encountered this bug on a Masscomp system, where ASCII NUL is
	returned in ioctl structures to indicate that there's no character you
	can type to cause the control function associated with the structure
	element.  I KNOW it's a pretty outre bug to be reporting.
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