virt-libvirt: Add configuration for virsh net-define/undefine test.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
virt-libvirt: Add test module for virsh net-define/undefine.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>