expose xbzrle cache miss rate
Signed-off-by: NChenLiang <chenliang88@huawei.com>
Signed-off-by: NGonglei <arei.gonglei@huawei.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>