Fix unintended switch case fall-through. Bug 21766174 Change-Id: I1428bcceb2fbf6c649632112f773c3a0625e3775 Reviewed-on: https://swiftshader-review.googlesource.com/3479 Reviewed-by: Nicolas Capens <capn@google.com> Tested-by: Nicolas Capens <capn@google.com>