Re: [libvirt] [PATCHv2] qemu: specify domain in host-side PCI addresses when needed/supported

This uses the new QEMU_CAPS_HOST_PCI_MULTIDOMAIN capability when present, for -devivce pci-assign, -device vfio-pci, and -pcidevice. While creating tests for this new functionality, I noticed that the xmls for two existing tests had erroneously specified an until-now-ignored domain="0x0002", so I corrected those two tests, and also added two failure tests to be sure that we alert users who attempt to use a non-zero domain with a qemu that doesn't support it. --- Change from V1: Before pushing, I decided that I really should be checking for non-0 domain for -pcidevice (an old deprecated method of specifying kvm device assignment) as well, rather than simply ignoring it (which is what I had been doing by choosing to "not support" it, as I indicated in the commit log for v1 of this patch). And by the time I had put in a check for non-0 domain to say "we don't support that", it was 90% of the way to just supporting it anyway. So this version adds support for non-0 domain to -pcidevice commandlines as well (and also adds an appropriate error message when non-0 domain isn't supported by the qemu, which will probably be the case 100% of the time anyway - *that* is the important change).