[roll third_party/pigweed] pw_sync: split out pw::sync::TimedMutex from pw::sync::Mutex

Original-Requires: pigweed-internal:11280
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/40083

third_party/pigweed Rolled-Commits: ecbabcc401c9c81..6f5b8fb1ff9a8b2
Roller-URL: https://ci.chromium.org/b/8850406581055836960
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8850406581055836960
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ieaf3c975c8d61da6809adc04ea7acd280a7be8a0
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/40340
Reviewed-by: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index ecbabcc..6f5b8fb 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit ecbabcc401c9c818008663424f25fd925b077ba6
+Subproject commit 6f5b8fb1ff9a8b2e025863187c7ec7c46fa74929