The anonymous shared memory are using shmid for image
name encoding which is unsigned long and we already
met scenario where high bits get strippped off thus
the restore failed.

Lets use unsigned long here, and because pagemap code
is shared between plain memory and anon shared memory
use unsigned long every where.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>