Windows: Media Protected if create on RO volume

Windows: Media Protected if create on RO volume

If there is an attempt to create a file/directory on a readonly
volume as indicated by the Volume Characteristics, return
STATUS_MEDIA_WRITE_PROTECTED immediately.  Do not bother contacting
the afsd_service.

Change-Id: I809adacbbc429166d9a0e308752e484400799cb8
Reviewed-on: http://gerrit.openafs.org/7647
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>