[roll third_party/pigweed] pw_build: Add -Wextra-semi to internal_strict_warnings

Create a new warnings config, internal_strict_warnings, to allow
for specifying new warnings without breaking downstream projects.

Add -Wextra-semi to the internal_strict_warnings config, making extra
semicolons an error in C++. Fix all instances of extra semicolons.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/98128

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 06cb12088f99bf1..4c4f6df161ce404
Roller-URL: https://ci.chromium.org/b/8810610285740720257
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8810610285740720257
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I667d6c501b8f803a4ca9024cf64bd9070016211f
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/99521
Bot-Commit: 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 06cb120..4c4f6df 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 06cb12088f99bf1c091230739eb0aa8dd84f9e4d
+Subproject commit 4c4f6df161ce40436c2db987522c13de145d1780