x86 does not strictly require this because it performs snooping to ensure
consistency, but it is essential on ARM and some other architectures.

Bug b/37478805

Change-Id: I9fad94571ec65b67132ba40c3e1814c63d6af468
Reviewed-on: https://swiftshader-review.googlesource.com/9429Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Nicolas Capens <capn@google.com>