Windows: Fix Redir link counting

Windows: Fix Redir link counting

Each object in AFS has a link count which tracks the number of
directory entries that refer to the FileId.  In the redirector
there is one ObjectInformationCB per FileId and one AFSDirectoryCB
for each directory entry.  When a directory entry is deleted perhaps
by delete on close it is important to ensure that the matching
ObjectInformationCB is not deleted unless the Link count drops to 0.

Change-Id: I2c7906d5881f93ed60697d40a0ea462f4567d443
Reviewed-on: http://gerrit.openafs.org/8480
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Rod Widdowson <rdw@steadingsoftware.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>