[libvirt] [PATCH 0/3] Support for marking domains as "tainted"

There are various configurations for virtual domains that we allow, but do not wish to actively support in production environments. The support situation is similar to that of binary only or non-GPL kernel modules, so borrow the kernel's idea of "tainting". When an undesirable configuration is used on a running VM, set a suitable taint flag and log a warning. OS distro bug triagers can see these warnings and decide whether to support users filing bugs in this scenarios