block: qemu-iotests - add check for multiplication overflow in vpc

This checks that VPC is able to successfully fail (without segfault)
on an image file with a max_table_entries that exceeds 0x40000000.

This table entry is within the valid range for VPC (although too large
for this sample image).

Cc: qemu-stable@nongnu.org
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
