vol: Handle large volume IDs in VLockFile

vol: Handle large volume IDs in VLockFile

VLockVolumeByIdNB currently cannot handle volume IDs larger than
2^31-1. Fix this by using struct flock64, F_SETLKW64, and F_SETLK64 in
the VLockFile functions where possible.

Thanks to Simon Wilkinson for pointing out F_SETLK64.

Reviewed-on: http://gerrit.openafs.org/4198
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 85edec7105dd653ed1d8046b69b8262281e97bba)

Change-Id: Iee09a8bc4a0aabbd12fe156940fa61d6947642e8
Reviewed-on: http://gerrit.openafs.org/5758
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Tested-by: Derrick Brashear <shadow@dementix.org>