This PR allows larger VHD image files. The size in question doesn't
necessarily mean the size of the VHD file on disk. The size is the total
size of the image emulated. This total size is in question.
Without this patch, the total size allowed is 65535 * 16 * 255, or
roughly 32gig.
With this patch, the total size is calculated by who the creator of the
image is, what the CHS values are, and possibly a total size of up to a
limit of 2TB.
Since the original code was ported from QEMU, I ported an updated QEMU
code snippet.
https://gitlab.com/qemu-project/qemu/-/blob/master/block/vpc.c?ref_type=heads#L305
This PR now allows VHD image files with a total size emulated less than
or equal to 2TB.
74ed550334