In a previous patch, we skipped zombies, but our pre-dump doesn't
support stopped tasks (Why does it not support them?), so let's
handle tasks which have parasite_ctl.

Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Andrew Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>