Re: [Libvir] [PATCH 0/2] Re-organize generation / handling of capabilities data

So I decided that we needed to have a internal API & structure to allow drivers to formally register & query their capabilities , and also add a central method for serializing it to XML. The following 2 patches implement this idea, and porting the Xen, QEMU and Test drivers to use it. This removes a lot of code duplication in XML formatting and makes the resulting code easier to follow, and should make it much quicker to adding capabilities info to new drivers too.