[libvirt] [PATCH] qemudDomainCreate check if domain is already active

Hi, currently virsh create foo.xml overwrites running domains. In case of qemu this leaves detached qemu processes around and the domain creation fails later on being unable to start other domains afterwards - not nice. Attached patch checks if we already have a running domain by that name and in this case refuses to create a new domain from xml by that name. Probably this check needs to be pushed further upward since this might affect other hypervisors too, haven't checked that though. Cheers, -- Guido