[$] WireGuard and the crypto API

When last we looked in on the progress ofthe WireGuard VPN tunnel toward themainline kernel, it seemed like the main sticking point had been overcome. The Zinc cryptography API used by WireGuard wasgenerally seen as a duplication of effort with the existing kernelcryptographic algorithms, so an effort to rework Zinc to use that existingcode seemed destined to route around that problem and bring WireGuard tothe mainline. In the six months since then, though, things have gonefairly quiet in WireGuard-land; that all changed based on a conversation atthe recent Kernel Recipesconference in Paris.