roll: third_party/pigweed 243485c..3e6a8fb (4 commits)

3e6a8fb:https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/297674 pw_string: Build and test the buffer example
e665314:https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/299414 pw_allocator: Remove unused ContiguousBlock::AsBytes() declaration
acbe158:https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/289638 pw_multibuf: Add MultiBuf v2
ee5db46:https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/297072 pw_result: Add tests for `expected<void, E>`

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: 243485c98e86c5..3e6a8fb4bd8360
Roll-Count: 1
Roller-URL: https://cr-buildbucket.appspot.com/build/8711690204445892161
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I9dce89e7416afe88ed70e20e5056aae64d289674
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/299457
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 243485c..3e6a8fb 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 243485c98e86c5a6340dfab6545e351b2f9fb296
+Subproject commit 3e6a8fb4bd8360db18b572a9734d2b7326edf765