r/vmhost: Update for latest libvirt

Some time ago, _libvirt_ was refactored to use separate daemons and
sockets for each of its responsibilities, and the original "monolithic"
`libvirtd` was made obsolete.  The Fedora packages have more recently
been adjusted to favor this new approach, and now default to omitting
the monolithic daemon entirely (when `install_weak_deps` is disabled).

One interesting packaging snafu, though, is that without the weak
dependencies, there is _no_ way for clients to connect by default.
Clients run `which virt-ssh-helper` to see if it is installed, which it
is, but `which` is not.  They then fall back to running `nc`, which is
_also_ not installed.  So even though the tools they actually need are
present, their logic for detecting this is broken.  As such, we need to
explicitly install `which` to satisfy them.

roles/vmhost/tasks/main.yml

@@ -5,12 +5,6 @@
   tags:
   - install
 
-- name: ensure libvirtd is configured
-  template:
-    src: libvirtd.conf.j2
-    dest: /etc/libvirt/libvirtd.conf
-    mode: '0644'
-
 - name: ensure libvirt can use nfs
   seboolean:
     name: virt_use_nfs
@@ -48,12 +42,24 @@
 
 - name: ensure libvirtd starts at boot
   service:
-    name: libvirtd
+    name: '{{ item }}'
     enabled: true
+  loop:
+  - virtqemud.socket
+  - virtnetworkd.socket
+  - virtstoraged.socket
+  tags:
+  - service
 - name: ensure libvirtd is running
   service:
-    name: libvirtd
+    name: '{{ item }}'
     state: started
+  loop:
+  - virtqemud.socket
+  - virtnetworkd.socket
+  - virtstoraged.socket
+  tags:
+  - service
 
 - name: ensure libvirt networks are defined
   virt_net: