With the upcoming dumping-via-netfilter patch, the DumpState
should not be related to NetClientState anymore, so move the
related information to a new struct called DumpNetClient.

Reviewed-by: Yang Hongyang <yanghy@cn.fujitsu.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>