Prevent runtime CPU detection in Haswell build

Change-Id: Ief0bfd026465a028ee26d970b92d9880f039e39c
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/772339
Reviewed-by: John Stiles <johnstiles@google.com>
Auto-Submit: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>