LU-8837 utils: make tools lightweight for lustre clients

LU-8837 utils: make tools lightweight for lustre clients

Currently the lustre tools are built for the server target even
for the case of clients rpms. Rework the tools so server specific
code is not built for the client only case. The UAPI headers
lustre_log_user.h, lustre_barrier_user.h, and lustre_disk.h are
server specific and are not available in the upstream client.
So make our tools not to depend on those headers in the client
case. With this change it is simple step to make our tools
buildable against upstream. Last move user land specific code
from lustre_disk.h to mount_utils.h. Don't install server UAPI
headers on client targets.

Change-Id: I6b2b780ac0e7338a085ee6a8747097f0097efca1
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/28315
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Tested-by: Jenkins
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>