Add ZPOOL device status information in zfsPoolDevStatusTable:

 # snmptable -v2c -cpublic localhost zfsPoolDevStatusTable
 SNMP table: BAYOUR-COM-MIB::zfsPoolDevStatusTable

                               zfsPoolDevName zfsPoolDevState zfsPoolDevRead zfsPoolDevWrite zfsPoolDevCksum
                          /var/tmp/zfs_file-1          online              0               0               0
                          /var/tmp/zfs_file-2          online              0               0               0
                          /var/tmp/zfs_file-3          online              0               0               0
  scsi-SATA_VBOX_HARDDISK_VB00c23763-14860ab9          online              0               0               0
  scsi-SATA_VBOX_HARDDISK_VB1f45d95c-477fd9c6          online              0               0               0
  scsi-SATA_VBOX_HARDDISK_VBa23b735b-e12dbf0c          online              0               0               0
  scsi-SATA_VBOX_HARDDISK_VBd15b7714-c746e03e          online              0               0               0
                                      spare-1          online              0               0               0