parallels: 2TB+ parallels images support

Parallels has released in the recent updates of Parallels Server 5/6
new addition to his image format. Images with signature WithouFreSpacExt
have offsets in the catalog coded not as offsets in sectors (multiple
of 512 bytes) but offsets coded in blocks (i.e. header->tracks * 512)

In this case all 64 bits of header->nb_sectors are used for image size.

This patch implements support of this for qemu-img and also adds specific
check for an incorrect image. Images with block size greater than
INT_MAX/513 are not supported. The biggest available Parallels image
cluster size in the field is 1 Mb. Thus this limit will not hurt
anyone.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Jeff Cody <jcody@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
