/etc/libvirt is not world-readable (at least on Fedora and RHEL) so
use sudo with the grep that checks whether we have already configured
libvirtd logging. Also, change the regex so we don't count commented
out logging config.
Change-Id: I67484b28aafd0fa828385321fa96d9141cb4cb59
Signed-off-by: Mark McLoughlin <markmc@redhat.com>