MFC r236155:

MFC r236155:
Import illumos changeset 13570:3411fd5f1589
1948 zpool list should show more detailed pool information

Display per-vdev information with "zpool list -v".
The added expandsize property has currently no value on FreeBSD.
This changeset allows adding expansion support to individual vdevs
in the future.

References:
https://www.illumos.org/issues/1948

Obtained from:	illumos (issue #1948)

git-svn-id: svn://svn.freebsd.org/base/stable/8@236840 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f