LU-8816 utils: Check /etc/hostid instead of failing for ZFS

LU-8816 utils: Check /etc/hostid instead of failing for ZFS

Since ZFS doesn't check /etc/hostid until a pool is created or
imported.  Check for it's existance instead of just failing after
spl_hostid is checked.

Test-Parameters: trivial

Signed-off-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Change-Id: Ia00b1e357c629ad6a7a2b636a2fc149036d03546
Reviewed-on: http://review.whamcloud.com/23804
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>