Windows: fail cm_CheckNTOpen if READ|DELETE for readonly file

Windows: fail cm_CheckNTOpen if READ|DELETE for readonly file

If the readonly file attribute is set (stored as a unix mode)
then a CreateFile operation should fail if the file is opened
for DELETE in combination with any other privilege.

LICENSE MIT

Change-Id: Ie8ebb6d230cf65d9ce2411bab2fcc4e561081505
Reviewed-on: http://gerrit.openafs.org/2660
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Jeffrey Altman <jaltman@openafs.org>