[libvirt] [PATCH 0/4] Changes to API/ABI for secrets handling

This series makes two changes to the public API and wire protocol ABI for the secrets handling support recently committed. As such this is a must fix before we do the release, since we can't break compatability once released. The first patch changes all the code to store UUIDs in raw format instead of printable format. This is important because it ensures that e3a9758f-b0c6-7a3a-ebb9-71a69c930289 is treated exactly the same as e3a9758fb0c67a3aebb971a69c930289, which is not the case with the currently committed code. It also makes the secrets and storage encryption XML parsers use the internal UUID handling APIs The second patch adds a new unique property to virSecretPtr. The "owner ID" is intended to be unique on a host wrt all secrets with matching usage type. This entails adding 2 APIs to querying the usage type, and another API to lookup a secret based on its usage. In testing the current code I frequently found myself getting into the situation where there were many secrets for the same volume which was not at all good. So if defining a secret to be used with a storage volume this ensures that you only ever have one secret associated with each storage volume path. The third patch ensures that when you query the XML for a qcow encrypted voluem, it will include the UUID of the secret. Previously if you created a volume, and then restarted libvirtd, the secret UUID would be lost. This patch is why we need the new API from the second patch virLookupSecretByUsage - without that it would be impossible to lookup the secret efficiently. THe final patch is a minor tweak to the RNG