Windows: Uninitialized TargetNameLength/Offset

In RDR_PopulateCurrentEntry it is possible for TargetNameLength and
TargetNameOffset to be uninitialized resulting in stack garbage being
returned to the redirector.  This can result in a blue screen.

Change-Id: Ifa306ba54bea3f26f1938cbd6bdc28521065299d
Reviewed-on: http://gerrit.openafs.org/10373
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>