vol: avoid MAXINT redefinition warning in vnode.c

vol: avoid MAXINT redefinition warning in vnode.c

Reviewed-on: http://gerrit.openafs.org/4179
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit b1d51d2a6030fb8aabdae1fedb6846dc7ef9fbca)

Change-Id: I8ea833cca442c67468982da31ed1b6fe04508a34
Reviewed-on: http://gerrit.openafs.org/5764
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Tested-by: Derrick Brashear <shadow@dementix.org>