null iconv outbuf

[Ilya N. Golubev]

Versions: all at least since 20-Apr-98

`charset.texi' says about iconv():

> If @var{outbuf} or @address@hidden is a null pointer, the
> conversion is performed but no output is available.

But `iconv.c' unconditionally dereferences `outbuf', at least when

!(__builtin_expect (inbuf == NULL || *inbuf == NULL, 0))

This causes segv when `outbuf' is a null pointer.

I do not submit a patch since I have not figured out which output
pointers are allowed by `__gconv' called by `iconv'.