roll: third_party/pigweed: pw_sync: [[nodiscard]] for try_lock() and similar functions

Ignoring the return value of a try_lock() function could be a serious
issue.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/229311

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 8d8bb25577cd054..2a34a2865e92cf7
Roller-URL: https://ci.chromium.org/b/8738421919757719585
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I153363a29d2a5d7501e0a27420520e110a667707
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/232103
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.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 8d8bb25..2a34a28 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 8d8bb25577cd0541b89db8a2771d1280679c1455
+Subproject commit 2a34a2865e92cf70c67186ef701882d27d8604d8