roll: third_party/pigweed pw_bluetooth_proxy: Add bazel build support

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/243874
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Original-Revision: a8c756860ae104ef5e87439ef4f8cc4fbbb2fab7

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: 542ffaac20c795..a8c756860ae104
Roll-Count: 1
Roller-URL: https://cr-buildbucket.appspot.com/build/8733060206373440801
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I68061907982ae23cb27c9e5199cbf0278f688586
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/244758
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 542ffaa..a8c7568 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 542ffaac20c79573e94a3936c448ebac8c288224
+Subproject commit a8c756860ae104ef5e87439ef4f8cc4fbbb2fab7