[libvirt] [PATCH 0/2] Add tx_alg attribute to interface XML for virtio backend

These two patches provide the ability to configure which of two algorithms is used on the TX side of the virtio-net-pci device. Details are in the comments for PATCH 2/2. There are also at least a couple of open questions about the patch, which are posed in the comments of 2/2. It's highly unlikely this patch will be pushed as-is - I'm sending it mostly to solicit comments on those questions.