Add support for IEEE 802.c stylc CRC32 computation to the sparse image tools

Add support for computing the CRC32 of the data when we make a sparse image,
and storing that CRC in the header.  Also update the simg2img tool that reads
sparse images to compute the CRC32 as it writes the image, and check to make
sure it matches what's in the header.

Change-Id: Id49b25bf820acb46ff981f3046fba5b24fd82c8d
5 files changed