9626 move 'static xuio_stats_t xuio_stats' to file where it use

illumos/illumos-gate@857c96d257470e097e846ab8886580991b329c32

Reviewed by: Yuri Pankov <yuripv@yuripv.net>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Dan McDonald <danmcd@joyent.com>
Author: Igor Kozhukhov <igor@dilos.org>