Once Subzero is pulled by Chromium (see
https://codereview.chromium.org/2695813002/),
we'll enable Subzero compilation on Windows.

Change-Id: I3464dbd98224b3ac602aef3c4a27596366d275b3
Reviewed-on: https://swiftshader-review.googlesource.com/8772Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>