[roll third_party/pigweed] bazel: Reduce log spam by suppressing DEBUG msg

These are quite spammy (especially when building the whole repo) and all
come from our third-party dependencies.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/122754

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 4f3608a2d723d4d..b668c21a71caeae
Roller-URL: https://ci.chromium.org/b/8795405309715655153
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I6c2037b419875f93939f255bfec1799186441766
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/122992
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 4f3608a..b668c21 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 4f3608a2d723d4de6dc46b2a52690da7d5c465d3
+Subproject commit b668c21a71caeae5b6f3ae7369bcf105c57867ea