Add (optional) support for the vsock protocol?

[psychon]

There is https://gitlab.freedesktop.org/xorg/lib/libxcb/-/merge_requests/27 which adds optional support for AF_VSOCK to libxcb. So far it saw no activity.

Since libstd doesn't support AF_VSOCK, I guess this would require using something like the vsock crate or doing the equivalent thing via nix (doesn't seem to be too complicated, but I haven't properly checked).

This just came up in quininer/x11-clipboard#38