roll: third_party/pigweed pw_multibuf: Include missing header

Original-Bug: b/371686453
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/240672
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Original-Revision: 01e206b56c43d114aea00383dd9c208800796d23

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: bf0f12d5ae3bb8..01e206b56c43d1
Roller-URL: https://ci.chromium.org/b/8734715857470073905
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I11e821ba01d03e7579b565136ae176147176cd90
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/240614
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index bf0f12d..01e206b 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit bf0f12d5ae3bb83c114079703664a005aa19159b
+Subproject commit 01e206b56c43d114aea00383dd9c208800796d23