Technically, the rest of the code *should* already
support changing this value and all related changes
should propagate properly. This allows a few dEQP
tests that were "unsupported" to now pass.

Change-Id: Ie99e1fba88e7642be447a380b78969365194ca5f
Reviewed-on: https://swiftshader-review.googlesource.com/3461Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>