Fix missing symbol errors in the MoM policy for ballooning

Change-Id: Id2b51a066ae94d70d012ad4c6ac5a4e0056be100
Signed-off-by: Martin Sivak <msivak@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/17110
Reviewed-by: Mei Liu <liumbj@linux.vnet.ibm.com>
Reviewed-by: Doron Fediuck <dfediuck@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>