[roll third_party/pigweed] pw_protobuf: Fix undefined pointer deref in fuzz test

The encoder fuzz test can sometimes attempt to dereference an undefined
pointer to get its address, which is technically undefined behavior.
This fixes that occurance.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/188281

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: fd1e0b737fdd7ab..43ce44233375111
Roller-URL: https://ci.chromium.org/b/8758533784911111425
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I6d2e46f0eabd0b2854db22203d95e1b893e9d29c
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/188336
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index fd1e0b7..43ce442 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit fd1e0b737fdd7ab2c2aaefd35b50b99448942f50
+Subproject commit 43ce442333751114c7edfdc1d5d8025f5920d051