roll: pigweed pw_toolchain: Move fuchsia_clang toolchains to pw_toolchain

Moves the c++ toolchain definitions for fuchsia clang to the pigweed
repository to avoid having to download the fuchsia_clang repository
during toolchain resolution.

Original-BUG: 346416385
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/237915
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Original-Revision: a9f2d91c85fe017e27ec94b7502984818cc7c723

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: 6422c9ae137ad3..a9f2d91c85fe01
Roller-URL: https://ci.chromium.org/b/8735626518794800801
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I2dee8b9a372077b3d12f07291a470d2c734564e2
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/quickstart/bazel/+/238345
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/MODULE.bazel b/MODULE.bazel
index 4b9ca32..21a1bca 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -49,8 +49,8 @@
     module_name = "pigweed",
     # ROLL: Warning: this entry is automatically updated.
     # ROLL: Last updated 2024-09-27.
-    # ROLL: By https://cr-buildbucket.appspot.com/build/8735626932666184849.
-    commit = "6422c9ae137ad37a9ec172dcd95f294ce5631f82",
+    # ROLL: By https://cr-buildbucket.appspot.com/build/8735626518794800801.
+    commit = "a9f2d91c85fe017e27ec94b7502984818cc7c723",
     remote = "https://pigweed.googlesource.com/pigweed/pigweed",
 )
 
@@ -58,8 +58,8 @@
     module_name = "pw_toolchain",
     # ROLL: Warning: this entry is automatically updated.
     # ROLL: Last updated 2024-09-27.
-    # ROLL: By https://cr-buildbucket.appspot.com/build/8735626932666184849.
-    commit = "6422c9ae137ad37a9ec172dcd95f294ce5631f82",
+    # ROLL: By https://cr-buildbucket.appspot.com/build/8735626518794800801.
+    commit = "a9f2d91c85fe017e27ec94b7502984818cc7c723",
     remote = "https://pigweed.googlesource.com/pigweed/pigweed",
     strip_prefix = "pw_toolchain_bazel",
 )