Windows: be explicit when mapping sharing violation

Windows: be explicit when mapping sharing violation

Only one lock acquistion failure should be mapping to
CM_ERROR_SHARING_VIOLATION.  That is CM_ERROR_LOCK_NOT_GRANTED.
Make it clear that is what we are doing.

Reviewed-on: http://gerrit.openafs.org/5299
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Jeffrey Altman <jaltman@openafs.org>
(cherry picked from commit a576ff1e53a539e88b9f3fa6b8132d4f161b0bd4)

Change-Id: I558c6989a2a8f4042129e2a60bcd340a7863222c
Reviewed-on: http://gerrit.openafs.org/6796
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>