xfsprogs: add CRC32c infrastructure

xfsprogs: add CRC32c infrastructure

Pull the generic crc32(c) code from the kernel and add it to libxfs.
Modify it to build in the libxfs environment, and drop the bigendian
CRC version as it is unused by XFS, which uses the little endian
version so that it can be hardware accelerated using native
instructions on x86-64 CPUs.

Also wire up the self-test code in the crc32 module to the build
infrastructure and make passing the self test a build dependency.
This prevents xfsprogs from being built on platforms that the CRC
algorithm does not work on and hence ensures the tools do not write
bad CRCs to disk as a result of a broken calculation.

Also pull the XFS CRC helper functions across in preparation for
using the CRC functions in libxfs.

XXX: something in the CRC table generation breaks the debian package
build. It fails to build libxfs as a dependency of mkfs.xfs. Works
fine outside the debian build environment, so I'm not sure what the
issue is yet. Most likely it is the execution path of the
gen_crc32table binary that is built...

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Rich Johnston <rjohnston@sgi.com>