LU-2675 liblustre: disable liblustre by default

LU-2675 liblustre: disable liblustre by default

liblustre is not used, nor is it tested, so don't build it by default.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: Ie2369d0163963d6e691b3787495b1b2155fe6111
Reviewed-on: http://review.whamcloud.com/9756
Tested-by: Jenkins
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>