gnulib's errno module was imported

[Eli Zaretskii]

> Date: Fri, 14 Nov 2014 13:21:01 +0000
> From: Pedro Alves <palves@redhat.com>
> CC: gdb-patches@sourceware.org, gregory.0xf0@gmail.com,        Joel Brobecker <brobecker@adacore.com>
> 
> > @@ -651,6 +652,7 @@ wchar_iterate (struct wchar_iterator *iter,
> >  	  switch (errno)
> >  	    {
> >  	    case EILSEQ:
> > +	    case ENOENT:
> >  	      /* Invalid input sequence.  We still might have
> >  		 converted a character; if so, return it.  */
> >  	      if (out_avail < out_request * sizeof (gdb_wchar_t))
> > 
> > This looks cleaner to me (some comments should be added, of course).
> 
> That was actually my first approach, but then:
> 
>  - I thought that having a central place to handle this
>    and to put the comment was cleaner than repeating the fix
>    in multiple places.
>  - That won't build on systems that EILSEQ and ENOENT are
>    defined to the same value (two switch cases with the same value).
>    Not sure there are any such systems, but given iconv.h's practice...

The last one is easy:

  	    case EILSEQ:
 +#if EILSEQ != ENOENT
 +	    case ENOENT:
 +#endif