Add "PerFileAccessCheck" registry value.

Add "PerFileAccessCheck" registry value.

The HKLM\SYSTEM\CurrentControlSet\Services\TransarcAFSDaemon
"PerFileAccessCheck" registry value (DWORD) is intended for
use only by developers who wish to test how Windows would
behave if a per-file access rights check was performed.

Windows performs all access rights checks using the directory
access rights.  There is no support for the VL_DFSFILESET flag.
During CreateFile() processing the requested access rights are
checked against the access rights reported by the file server
for the directory.  If the reported rights are more permissive than
the effective access rights for the file, Windows applications
(including the Explorer Shell) will behave quite poorly.  In other
words, if the request is for write privilege and the CreateFile()
successfully opens the file with write privilege, subsequently
reporting an access denied on a WriteFile() call will result in
very poor behavior.

The addition of this option is simply to make it easier on
developers to test various prototype solutions for adding per-file
access rights.

LICENSE MIT

Reviewed-on: http://gerrit.openafs.org/15
Reviewed-by: Asanka Herath <asanka@gmail.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Verified-by: Jeffrey Altman <jaltman@openafs.org>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>