The <sys/uio.h> system header doesn't exist on all host platforms. Code
should include "qemu/osdep.h" instead to avoid build breaks on plafforms
that don't define CONFIG_IOVEC (like win32, if it is to support 9p one day).

Acked-by: Cédric Le Goater <clg@kaod.org>
Acked-by: Michael Fritscher <michael@fritscher.net>
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>