roll: third_party/pigweed: pw_bluetooth_sapphire: Handle flexible array warning

Use `PW_MODIFY_DIAGNOSTIC_CLANG` to disable a flexible array extension
warning when building with clang.

Original-Bug: b/355511476
Test: fx test //src/connectivity/bluetooth/core/bt-host

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1095796
GitOrigin-RevId: e7361b6cda5c6232897daf1ff935a61809c6ccd4
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/230554

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: c8ee64266138999..cdd0561a19e7839
Roller-URL: https://ci.chromium.org/b/8738784951132156385
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Iedf1c17bf9c8eb062272157fc38dfab180ad505b
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/231754
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
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 c8ee642..cdd0561 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit c8ee64266138999969d90af8e1672bb2bfc3f57e
+Subproject commit cdd0561a19e783910f10ab8c37210c169fb27715