Calling GSSetConstantBuffers with real data causes a device removed
error on 9_3. We therefore ensure that ANGLE doesn't call it on 9_3.

Change-Id: I151a74ee7ea81fc4b795d8bf10d5e5c42bfe7c86
Reviewed-on: https://chromium-review.googlesource.com/236042Tested-by: Austin Kinross <aukinros@microsoft.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>