[third_party/pigweed] Roll 2 commits

3839477fad5af9e pw_presubmit: Exclude bazel failures by target
af46d766c7a8fae WORKSPACE: format with buildifier

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: de62a2de159d920..3839477fad5af9e
Roller-URL: https://ci.chromium.org/b/8806283958982853873
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8806283958982853873
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I1d807ab180eac6715b2708bb49216d2ff17666e3
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/105605
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Bot-Commit: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index de62a2d..3839477 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit de62a2de159d920d2b19ca414b4d41681310789e
+Subproject commit 3839477fad5af9e02d6176d2c402caacaa9b1ff1