Windows: AFSRemoveCaseInsensitiveDirEntry corrections

Windows: AFSRemoveCaseInsensitiveDirEntry corrections

If there is a fLink but no parentLink for the DirEntry being
removed, return the fLink as the new value for *RootNode.

This patch set also includes two changes that improve readability
but do not alter the behavior.

Change-Id: I112265798df9d46c83ffacddc7d97ad0f6fce5bf
Reviewed-on: http://gerrit.openafs.org/5638
Reviewed-by: Rod Widdowson <rdw@steadingsoftware.com>
Reviewed-by: Peter Scott <pscott.kd@gmail.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>