Windows: Permit renames of open files

Windows: Permit renames of open files

AFS does not impose a restriction on renames of open files.
Failure to permit the rename can cause problems if an anti-malware
service opens the file immediately after the application performing
the rename does so.

Change-Id: Ib23a6a893c5c575e89b8a817faec4c11300a04b7
Reviewed-on: http://gerrit.openafs.org/6503
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Peter Scott <pscott@kerneldrivers.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>