Add libvirtd start logging test case.

This case check error messages in libvirtd logging when libvirtd
starting.

Implemetent test cases:
with_iptables:  Simply start libvirtd when using iptables service
                as firewall.
with_firewalld: Simply start libvirtd when using firewalld service
                as firewall.

Signed-off-by: Hao Liu <hliu@redhat.com>