xfsprogs: updata libxlog to current kernel code

xfsprogs: updata libxlog to current kernel code

Update the libxlog log recovery code to match the current 3.8-rc2
kernel code and ensure all the callers work correctly.

Note: while this introduces CRC validation infrastructure, it is
currently short-circuited as it is not clear what to do with log
buffers that fail CRC checking. We're only reading the log to
determine it is clean/dirty or dumping the contents for analysis, so
it's not clear what to do with CRC validation errors yet, or even
if there is any commonality with the kernel handling. This will need
to be revisited as the situation clarifies.

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>