block/parallels: check new image size

Before this patch incorrect image could be created via qemu-img
(Example: qemu-img create -f parallels -o size=4096T hack.img),
incorrect images cannot be used due to overflow in main image structure.

This patch add check of size in image creation.

After reading size it compare it with UINT32_MAX * cluster_size.

Signed-off-by: Klim Kireev <proffk@virtuozzo.mipt.ru>
Signed-off-by: Denis V. Lunev <den@openvz.org>
Message-id: 1469639300-12155-1-git-send-email-den@openvz.org
CC: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
