zfs: import zpool and zfs command-line utilities

Imported with no change from FreeBSD 245655.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
bsd: import libuutil

Imported with no change from FreeBSD 245655.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
bsd: random imports

Import FreeBSD files, changeset 245655.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
bsd: import libumem

Imported from FreeBSD 245655, no changes.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>