cpplib: fix for another obscure macro-expansion bug

[Dave Brolley]

Zack Weinberg wrote:

> On Tue, 29 Sep 1998 17:49:53 -0400, Dave Brolley wrote:
>
> >I see where you moved the code to remove the no-reexpand marker so that it
> >will be executed in this case, but what does the change of \n to @ and the
> >handling of the whitespace markers address? Do yo have a test case that
> >shows how those bits of code were broken?
>
> I don't have a test case, but \n is no longer used as escape, so the code
> that checks for a no-reexpand marker at the end of the macro was incorrect.
> The change to the whitespace markers is necessary for the same reason; \n is
> included in is_space, @ isn't.

OK. It looks like your test case for the correction to this patch exercises the
code.

This patch looks OK to me now.

Dave