roll: third_party/pigweed targets: Remove implicit extern C

`main` function is by default considered `extern C` and adding it
explicitly creates a pedantic warning causing failures with new clang
toolchain.

Original-Bug: 366374135
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/237092
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Original-Revision: a5a199593f1375177d5805f882f303d4c8b8cea2

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: cc365b0d0e8087..a5a199593f1375
Roller-URL: https://ci.chromium.org/b/8736047718185190801
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I82d94ab6ef17dbe68423dad7a25974fef27d6f6d
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/237282
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index cc365b0..a5a1995 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit cc365b0d0e8087f01a9fd91d58a91448d1bcb963
+Subproject commit a5a199593f1375177d5805f882f303d4c8b8cea2