[IOT-1769] Add OC_STACK_NOT_ACCEPTABLE status code

[IOT-1769] Add OC_STACK_NOT_ACCEPTABLE status code
to fix build break.

Change-Id: I8590a9e78df7e5f8ba5c4938dad8d3b7d277b0bc
Signed-off-by: Alex Kelley <alexke@microsoft.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/16635
Reviewed-by: Kevin Kane <kkane@microsoft.com>
Reviewed-by: Srikrishna Gurugubelli <srikguru@microsoft.com>
Tested-by: jenkins-iotivity <jenkins@iotivity.org>
Reviewed-by: Phil Coval <philippe.coval@osg.samsung.com>
Reviewed-by: Dan Mihai <Daniel.Mihai@microsoft.com>