[libvirt] [PATCH] provide the object name on lookup error

There were a number of places where the object name was not not reported, based on the use I don't think the string could be NULL in any of those. I also fixed a few POOL error which were really VOLume ones. Daniel -- Daniel Veillard | libxml Gnome XML XSLT toolkit http://xmlsoft.org/ daniel@veillard.com | Rpmfind RPM search engine http://rpmfind.net/ http://veillard.com/ | virtualization library http://libvirt.org/