roll: third_party/pigweed pw_toolchain: Add msan toolchain feature

While msan currently has false positives and can't be enabled in CI,
it can still produce useful findings when run manually in the meantime.

Original-Bug: 234876100
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/274512
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Original-Revision: b3e7f598fda9d03aca04e26ae0a691a117404473

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: 15e7d200f03965..b3e7f598fda9d0
Roll-Count: 1
Roller-URL: https://cr-buildbucket.appspot.com/build/8720740999641452673
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ie1dd8c4c72b2abf55476d01b0073dfb0644a87b5
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/274574
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 15e7d20..b3e7f59 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 15e7d200f03965658d73a904bb8496398caa79d7
+Subproject commit b3e7f598fda9d03aca04e26ae0a691a117404473