Windows: IO Subsystem Trace modifications

Display file offsets consistently as %0I64X.

Change-Id: Ib1484ef99fbf055ec4bc00e17469e0daa9661e96
Reviewed-on: http://gerrit.openafs.org/9129
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Rod Widdowson <rdw@steadingsoftware.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>