Windows: modify PopulateCurrentEntry follow mp rules

It is always safe to read the mount point target data, it is not
always safe to evaluate the volume id since the VLDB might not be
reachable.

For directory enumerations do not evaluate the target Fid.  Only
do so for eval by name and by id requests.

Change-Id: Ifa0e84b2e9fb0822dceb9d719a47c541fed2a2bf
Reviewed-on: http://gerrit.openafs.org/10153
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>