fix hotspot build failures with -D_FORTIFY_SOURCE=2 and -Wformat=1

[Florian Weimer]

* David Holmes:

> And here:
>
> -    ::write(defaultStream::output_fd(), s, (int)strlen(s));
> +    ssize_t rv = ::write(defaultStream::output_fd(), s, (int)strlen(s));
>
> if we are ignoring the return value anyway (which might be the real
> error here!)

Looks like a bug to me because the file descriptor might refer to a
terminal.