LU-11555 utils: ZFS check multihost enabled in read_ldd()

LU-11555 utils: ZFS check multihost enabled in read_ldd()

For ZFS check that multihost is enabled if failover host is defined.
Print a warning if it's not.

Test-Parameters: trivial mdtfilesystemtype=zfs ostfilesystemtype=zfs
Signed-off-by: Nathaniel Clark <nclark@whamcloud.com>
Change-Id: Iddb5871afc6fb6808a25921c8d3e8516d675f15c
Reviewed-on: https://review.whamcloud.com/33491
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Olaf Faaland-LLNL <faaland1@llnl.gov>
Reviewed-by: Oleg Drokin <green@whamcloud.com>