If a systemd socket uses /var/run in its path, systemd prints a warning
at runtime

[   15.139976] systemd[1]: /usr/lib/systemd/system/virtlockd.socket:5:
  ListenStream= references a path below legacy directory /var/run/,
  updating /var/run/libvirt/virtlockd-sock → /run/libvirt/virtlockd-sock;
  please update the unit file accordingly.

This minimal change updates the socket unit files to honour the
$runstatedir path.

There's no functional change by default yet since both expressions
expand to the same value.
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

Prepare for reusing libvirtd socket unit files with other daemons by
making various parts of their config conditionally defined by the make
rules.
Reviewed-by: NChristophe de Dinechin <dinechin@redhat.com>
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

Substitute in the @sysconfigdir@ value instead of /etc.
Reviewed-by: NChristophe de Dinechin <dinechin@redhat.com>
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

Certain libvirtd.conf settings are not honoured when using systemd
socket activation.

Certain systemd unit file settings must match those defined in
libvirtd.conf for systemd socket activation to work with systemd
version < 227, otherwise libvirtd cannot determine which inherited
FD to use for which service.
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

We don't do socket activation of libvirtd, since we need to
unconditionally start libvirtd in order to perform autostart. This
doesn't mean we can't have systemd socket units. Some use cases will
not need libvirt's autostart & are thus free to use activation.
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>