Windows: Obtain File Attribs for DFS Link target

The AFSRetrieveFileAttributes() function is used to acquire the
attributes for an AFS symlink.  The result is either returned directly
to the application or used internally to determine the attributes
to be exposed by reparse points.

If the evaluated symlink crosses a DFS Link the redirector cannot
return the request to IO Manager to evaluate the target.  Instead
the redirector must handle the request internally and attempt to
read the attributes of the target object.

Change-Id: If14df8dc41e13fd59b524fdb575c46abab1dfc2f
Reviewed-on: http://gerrit.openafs.org/11399
Reviewed-by: Peter Scott <pscott@kerneldrivers.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>