volinfo: refactor size counters

Put the volume, partition, and server size counters into structures.

Reviewed-on: http://gerrit.openafs.org/4733
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 4e97b2e5f820e07ffbaf8407cca18c536d9d0f67)

Change-Id: I1d6f5d31d359a6e89dad34c7319b6bbd4d121ed6
Reviewed-on: http://gerrit.openafs.org/11251
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>