Windows: Service processing for Symlink creation

Initial support for symlink creation via the Win32 CreateSymbolicLink api.
Add support for AFS_REQUEST_TYPE_CREATE_SYMLINK redirector requests via
the new RDR_CreateSymlinkEntry() function.

Since CreateSymbolicLink api creates a new directory or file object and
then assigns the Microsoft reparse tag data to that object,
RDR_CreateSymlinkEntry must first delete the empty directory or file and
then create the new symlink object in its place.  If the empty object can
be removed but the symlink cannot be created, STATUS_FILE_DELETED is
returned to indicate to the redirector that a failure occurred that
changed the state of the directory without creating a new object.

If the empty object cannot be removed, a STATUS_ACCESS_DENIED error will
be returned and the empty object will unfortunately remain in the AFS
directory.

Target path translation is performed.  Absolute AFS paths are stored in
UNIX notation.  Absolute non-AFS UNC and device paths are prefaced with
"msdfs:".

Reviewed-on: http://gerrit.openafs.org/9425
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit 75ee4fb1afce75316fd05b013b36a24f218118dc)

Change-Id: Id4d01ab0c2bff817b46ef4ee6e8f9ba2ff0a6c59
Reviewed-on: http://gerrit.openafs.org/9573
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Windows: RDR_UpdateFile dscp != scp

Do not set bScpLocked when obtaining scp->rw as scp != dscp.

Reviewed-on: http://gerrit.openafs.org/9553
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit 002d97363f01e0099519c35fc2f5a2af4305267e)

Change-Id: Ic22e2f4e6f4eaf87f2931df3c1d3a08cc0ce5b72
Reviewed-on: http://gerrit.openafs.org/9574
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>