roll: third_party/pigweed bazel: Generate compile commands for Fuchsia

For now, this just includes some targets that are only buildable in
Bazel and therefore can't have compile commands generated by GN.

Fixes: 368654273
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/237133
Original-Revision: 6b20a021cf616e20749c3eeb9cdbf8ebff12dcca

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: da9a7e7cc2bd98..6b20a021cf616e
Roller-URL: https://ci.chromium.org/b/8736224576174931985
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I738c3b225c7369904b0b6e5b87cb79935e881e84
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/237083
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Lint: Lint 🤖 <android-build-ayeaye@system.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 da9a7e7..6b20a02 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit da9a7e7cc2bd983d428949a6f5d85b9757b5178f
+Subproject commit 6b20a021cf616e20749c3eeb9cdbf8ebff12dcca