This patch adds the new option (--live, --config and --current) to
"virsh vcpupin" command. The behavior of above aption is the same as
that of "virsh setmem", "virsh setvcpus", and whatnot.
When the --config option is specified, the command affects a persistent
domain, while --live option is specified, it affects a running (live) domain.
The --current option cannot be used with --config or --live at the same
time, and when --current is specified, it affects a "current" domain.