Ressurect the disk-drive-network-iscsi-auth and disk-drive-network-rbd-auth
tests. Make adjustments to the args and xml file to be compatible with
other changes made to the non "-auth" so that the only difference is the
authentication information.
Adjust the qemuargv2xmltest.c to filter out "<secret" and "</auth>" since
the args -> xml has no concept of usage it doesn't get printed. This results
in the </auth> being printed on the same line as "<secret" and the secret
XML is not closed - a bit of an issue, but soon to be fixed.
<controller type='pci' index='0' model='pci-root'/>
is auto-added to pc* machine types.
Without this controller PCI bus 0 is not available and
no PCI addresses are assigned by default.
Since older libvirt supported PCI bus 0 even without
this controller, it is removed from the XML when migrating.
