libnl: make link cache optional for link/route/addr_info

Change-Id: I0e6aaac0bdb58a0052b25f588e11de03bde3e12f
Signed-off-by: Petr Horáček <phoracek@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/32949
Reviewed-by: Antoni Segura Puimedon <asegurap@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>