[third_party/pigweed] Roll 2 commits

3b68c84d2909ecf pw_build: Upstream build script fixes
c0bcf5adae9ee7b pw_sync: Improve Borrowable lock traits and annota

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 10eb559000cfb5d..3b68c84d2909ecf
Roller-URL: https://ci.chromium.org/b/8774477243902476321
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: If228d7ee19bd97f4256fac247dba268a2327225e
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/160150
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 10eb559..3b68c84 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 10eb559000cfb5d8f9a18dcb9950aa1244c5deaa
+Subproject commit 3b68c84d2909ecf33700ad7967c3041663d39f78