[third_party/pigweed] Roll 4 commits

081fda08421df2a pw_proto_compiler: strip_import_prefix + options
8a6f44e41e80bf8 pw_build: Remove FUZZTEST_OPTS
aaf126b137a6c24 pw_unit_test: Update docs
dc5ef2e7790bfa5 docs: Add protobuf style guide

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 64bfe3952506478..081fda08421df2a
Roller-URL: https://ci.chromium.org/b/8754136114501474593
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I1876b13f1d29cd3e36fd0728246732237194f6db
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/kudzu/+/195210
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 64bfe39..081fda0 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 64bfe39525064789c2f79efa9f2d9afe06a0af0c
+Subproject commit 081fda08421df2ad3592be7d8cfd138566f19685