Windows: Interlocked ops for cm_scache

Windows: Interlocked ops for cm_scache

Use Interlocked operations for cm_scache flags and mask field
changes.

Reviewed-on: http://gerrit.openafs.org/5193
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>
(cherry picked from commit 75297d4439bb30ddd9968805aecf2cc2812bfdf0)

Change-Id: Ic10b726eb5791c7c8d3eb7c3ad529522f627f73c
Reviewed-on: http://gerrit.openafs.org/5214
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>