roll: third_party/pigweed 9e4c976..ce7b2d9 (4 commits)

ce7b2d9:https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/253595 pw_grpc: Allocate contiguous multibufs only
8b5abe6:https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/253612 pw_bluetooth_proxy: Fix missing notify of queue space available
9720483:https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/253554 pw_presubmit: Bazel lockfile check
5a62fe4:https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/253332 blog: Shaping a better future for Bazel C/C++ toolchains

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: 9e4c976345d4d2..ce7b2d9d8993f4
Roll-Count: 1
Roller-URL: https://cr-buildbucket.appspot.com/build/8728822157868502913
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ia2cb376b6e7e5c3f93f78e85e360adbcc4c70a31
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/253852
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 9e4c976..ce7b2d9 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 9e4c976345d4d2de321e17853e9fb86493ff2200
+Subproject commit ce7b2d9d8993f43ef7300d63799cf777ac00aa09