qemu: add castagnoli crc32c checksum algorithm

This adds the Castagnoli CRC32C algorithm, using the 0x11EDC6F41
polynomial.

This is extracted from the linux kernel cryptographic crc32.c module.

The algorithm is based on:

Castagnoli93: Guy Castagnoli and Stefan Braeuer and Martin Herrman
             "Optimization of Cyclic Redundancy-Check Codes with 24
              and 32 Parity Bits", IEEE Transactions on Communication,
              Volume 41, Number 6, June 1993
block: vhdx header for the QEMU support of VHDX images

This is based on Microsoft's VHDX specification:
    "VHDX Format Specification v0.95", published 4/12/2012
    https://www.microsoft.com/en-us/download/details.aspx?id=29681

These structures define the various header, metadata, and other
block structures defined in the VHDX specification.
block: initial VHDX driver support framework - supports open and probe

This is the initial block driver framework for VHDX image support
(i.e. Hyper-V image file formats), that supports opening VHDX files, and
parsing the headers.

This commit does not yet enable:
    - reading
    - writing
    - updating the header
    - differencing files (images with parents)
    - log replay / dirty logs (only clean images)

This is based on Microsoft's VHDX specification:
    "VHDX Format Specification v0.95", published 4/12/2012
    https://www.microsoft.com/en-us/download/details.aspx?id=29681
block: add read-only support to VHDX image format.

This adds in read-only support to the VHDX image format.  This supports
reads for fixed-size, and dynamic sized VHDX images.

Differencing files are still unsupported.

The image must be opened without BDRV_O_RDWR set, because we do not
yet update the headers.  I.e., pass 'readonly=on' in the drive image
options from the QEMU commandline.
block: add header update capability for VHDX images.

This adds the ability to update the headers in a VHDX image, including
generating a new MS-compatible GUID.

As VHDX depends on uuid.h, VHDX is now a configurable build option.
If VHDX support is enabled, that will also enable uuid as well.

To enable/disable VHDX:  --enable-vhdx, --disable-vhdx
vhdx debug print