vol: Make ntops functions 64-bit capable

vol: Make ntops functions 64-bit capable

Add 64-bit offset and length support to ntops functions.

Reviewed-on: http://gerrit.openafs.org/3708
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 3c25ae062a30c83f6dfb388f31878555d6cb63d7)

Change-Id: I5a39e1c255cf5a28e53e9f96d4faf8a6a7e7ebf6
Reviewed-on: http://gerrit.openafs.org/3843
Tested-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>