bug#34123: A patch to fix reading EOF characters in non-interactive mode

[Eli Zaretskii <eliz@gnu.org>]

> From: Shawn Presser <shawnpresser@gmail.com>
> Date: Fri, 18 Jan 2019 10:20:54 -0600
> Cc: 34123@debbugs.gnu.org
> 
> It's non-interactive:
> 
> arc> |noninteractive|
> t
> 
> (The expression |noninteractive| in arcmacs is equivalent to evaluating 'noninteractive in emacs lisp.)
> 
> The runtimes start by invoking emacs using `emacs -Q --script ...`, so it's always noninteractive. And in
> general for writing shell scripts rather than repls, it's important to be in noninteractive mode. But it's equally
> important to have the ability to prompt the user from a shell script, and for the user to be able to cancel by
> using ^D without causing stdin errors on all subsequent prompts.

I think we are miscommunicating, since your usage involves Emacs
reading from the terminal.  That is not noninteractive in my book.
What I mean by noninteractive is when stdin is not connected to a
terminal.  Your proposed patch affects that case as well, doesn't it?