Make unixuser's vid advisory

Make unixuser's vid advisory

The 'vid' element of the unixuser structure was performing two
functions. It was used in debug messages to clarify which user's
token had expired and, in a few locations, to signify whether the
user had tokens or not.

This patch removes this dual usage. 'vid' is renamed to viceId, so
all uses are found and fixed. Where it is used for debugging, it remains,
but we only set the viceId for a user when we first use an rxkad token
on that context. Other uses of 'vid' have been replaced with tests
against the UHasTokens flag in the user's states.

Change-Id: Ifc0306a34fb7360810c792215e55e783f1dd062c
Reviewed-on: http://gerrit.openafs.org/2581
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>