roll: third_party/pigweed 690cacd..15e7d20 (3 commits)

15e7d20:https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/273972 roll: Clang
124b7de:https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/274392 pw_env_setup: Update CIPD path in docstring
29e85fe:https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/274213 pw_container: Have FlatMap ctor support move-only values

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: 690cacd988fd7d..15e7d200f03965
Roll-Count: 1
Roller-URL: https://cr-buildbucket.appspot.com/build/8720749817734183073
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I9d1ab3d1acb5292aa0cdab422f002da5a7ac1396
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/274473
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 690cacd..15e7d20 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 690cacd988fd7d664235a90fd83a52ea56b8a222
+Subproject commit 15e7d200f03965658d73a904bb8496398caa79d7