Windows: rx_Write failures must be processed

Windows: rx_Write failures must be processed

The error code returned by rx_Write takes precedence under
all circumstances over the error returned by EndRXAFS_StoreData.

cm_ReleaseBIOD must apply the error code to all buffers in the
BIOD list.

cm_ReleaseBIOD accepts an error code, not a boolean indicating
failure.

Fix a related signed/unsigned error.

FIXES 125351

LICENSE MIT

Reviewed-on: http://gerrit.openafs.org/396
Tested-by: Asanka Herath <asanka@secure-endpoints.com>
Reviewed-by: Asanka Herath <asanka@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@openafs.org>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>