mount.glusterfs: remove use of LD_LIBRARY_PATH

BUG: 989858
Change-Id: Id7c3929a179e151b6d60d3382bd5310187bb2aa6
Signed-off-by: Amar Tumballi <amarts@redhat.com>
Reviewed-on: http://review.gluster.org/5423
Reviewed-by: Bala FA <barumuga@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>