LU-4681 utils: Fix error message when using hostname

LU-4681 utils: Fix error message when using hostname

When running llmount.sh for setting up and testing a filesystem
if the system does not have an accurate line in /etc/hosts the build
fails with a cryptic error message.

This patch adds a little more information to the error message
directing the admin to fix the /etc/hosts error.

Signed-off-by: Bobbie Lind <bobbie.j.lind@intel.com>
Change-Id: I426c1f05d2ab5dedc56bd587072882cf78c1bd43
Reviewed-on: http://review.whamcloud.com/9848
Tested-by: Jenkins
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>