[third_party/pigweed] Roll 4 commits

9c1540d84fb3aa8 pw_web: Create log store and enable download logs
ff074e72f67c37f pw_unit_test: Fix googletest backend
277297be6fea9fc bazel: Mark more targets testonly
ea6ef4f4f5bd82b pw_config_loader: Support custom overloading rules

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 4a4b17d29ec1087..9c1540d84fb3aa8
Roller-URL: https://ci.chromium.org/b/8755261147935377025
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I6b49140703bcc559d9868825d70d12ff29d65ea9
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/193710
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 4a4b17d..9c1540d 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 4a4b17d29ec10874889a4275075bab2069b8afef
+Subproject commit 9c1540d84fb3aa80e140c51b2f58a273cd345fc2