Squash a frightening number of warnings from XBSA-related code

Squash a frightening number of warnings from XBSA-related code

Mostly missing prototypes and mismatched format strings, but also some
more disturbing bugs.

Change-Id: I9a10728c7da645bb562374a3598414484de33f4d
Reviewed-on: http://gerrit.openafs.org/11960
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Daria Brashear <shadow@your-file-system.com>