[roll third_party/pigweed] third_party: Mute build warnings of SSL libraries

Mute build warnings of MbedTLS/BoringSSL

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/51321

third_party/pigweed Rolled-Commits: 02364df0d4a1f24..81c4a0bd020d301
Roller-URL: https://ci.chromium.org/b/8843073602911301393
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8843073602911301393
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I29e2a08f02e230d20dd4faf456aff108b0b8212e
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/51561
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 02364df..81c4a0b 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 02364df0d4a1f24015dd26cf2f7eab8c0d5e0a49
+Subproject commit 81c4a0bd020d301a8dd16e5ad8c6718c32d00588