roll: third_party/pigweed 3 commits

3bf60a7ec0808b4 pw_preprocessor: Add docs metadata
942045675a03c39 pw_malloc: Add docs metadata
853213c54c4eeac pw_watch: Do not watch bazel-* symlinks

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 91a2499caca5df9..3bf60a7ec0808b4
Roller-URL: https://ci.chromium.org/b/8744211452860419953
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Icde116a38991c82a61a06e702de5692c6342bbdc
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/217991
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 91a2499..3bf60a7 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 91a2499caca5df9a85dacd29cb008bd5bafdaace
+Subproject commit 3bf60a7ec0808b4fa08c1f3b314973b9543f39ae