spec: Restart libvirtd in posttrans

spec: Restart libvirtd in posttrans

When upgrading libvirt packages, there's no strict ordering for the
installation or removal of the individual libvirt sub packages. Thus
libvirt-daemon may be upgraded (and its %postun scriptlet) started
before all sub packages with driver libraries are upgraded. When
libvirt-daemon's %postun scriptlet restarts the daemon old drivers may
still be laying around and the daemon may crash when it tries to use
them.

Let's restart the daemon in %posttrans to make sure libvirtd is
restarted only after all sub packages are at the same version.

https://bugzilla.redhat.com/show_bug.cgi?id=1464300

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>