The implementation is pretty straightforward. When dumping per-thread
misc data with parasite, collect one, then write in thread_core_info.

On restore wait for creds restore and put the value back (some creds
changes drop it to zero).
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>