io: handle data_size of -1 as unlimited data in print_iovec

[strace] / .mailmap

# Map git author names and email addresses to canonical/preferred form.
<ak@linux.intel.com>    <ak@suse.de>
<dgilbert@redhat.com>   <dave@treblig.org>
<holger@freyther.de>    <zecke@selfish.org>
<kirill@shutemov.name>  <kirill.shutemov@linux.intel.com>
<schwab@linux-m68k.org> <schwab@redhat.com>
<schwab@linux-m68k.org> <schwab@suse.de>
<vda.linux@googlemail.com>      <dvlasenk@redhat.com>
Eugene Syromyatnikov    <evgsyr@gmail.com>