Just a safety belt that we're not doing stupid things.

Change-Id: I092b0755d151a559f793e1a9f30b17ef52626d10
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/28389
Presubmit-Ready: Ben Clayton <bclayton@google.com>
Tested-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>