virsh: Introduce new hypervisor-cpu-compare command
    
    This command is a virsh wrapper for virConnectCompareHypervisorCPU.
    
    Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
    Reviewed-by: Ján Tomko <jtomko@redhat.com>
    Reviewed-by: Collin Walling <walling@linux.ibm.com>