Extend domdirtyrate-calc virsh api with mode option, either
of these three options "page-sampling,dirty-bitmap,dirty-ring"
can be specified when calculating dirty page rate.
Signed-off-by: Hyman Huang(黄勇) <huangy81@chinatelecom.cn>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>