[libvirt] [PATCH 0/5] Add virConnectListDefinedInterfaces/NumOfDefinedInterfaces

This patch adds everything but the backend implementation of two APIs that were requested during review of my patch to add virsh commands that expose the virInterface* API. These count and list interfaces on the host that are currently inactive (ie "down"). virConnectListInterfaces and virConnectNumOfInterfaces will list/count *only* those interfaces that are currently active. With these functions in place, I'll be able to add the "--inactive" and "--all" flags to iface-list, as suggested by danpb. Implementation of the backend of these two functions is waiting for two things: 1) supporting code in libnetcf, and 2) implementation of the rest of the backend driver functions for virInterface* (ready in the wings and waiting to go).