[bug#27887] [PATCH] services: Add libvirt services

[Ryan Moe]

> Hmm, ok. If you don't have any strong opinions on how to fix this,
> wrapping the libvirtd binary in the libvirt package is straightforward
> and common. I've attached a patch that does this.

I don't know enough about Guix yet to suggest a better way to fix
this, but your patch looks like a reasonable way to handle this to me.
I'll do some more testing and send an updated patch.