[roll third_party/pigweed] pw_tokenizer: Migrate the design content

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/151446

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 5d2525d92d5bc4f..b9db649376bb473
Roller-URL: https://ci.chromium.org/b/8778445250473780129
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Idd157fb6c2f3c8b64618b7c152c340647a8c11e3
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/151539
Bot-Commit: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 5d2525d..b9db649 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 5d2525d92d5bc4fd5e45bedfed9da6f3a0adf5f3
+Subproject commit b9db649376bb4737b7a23bea4aa57c8d6fec15f8