roll: third_party/pigweed pw_toolchain: Switch arm_clang to rules_cc toolchains

Switches the arm_clang toolchain to use rules_cc toolchains.

Original-Bug: b/346388161
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/237196
Original-Revision: 60e7e4fa95cbabcd0b6cb8948d90d8ba15e92919

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: 7d78c549c47d4b..60e7e4fa95cbab
Roller-URL: https://ci.chromium.org/b/8734516085076910705
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I0b8b809a6a011d30434f473f590f191197061001
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/241292
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 7d78c54..60e7e4f 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 7d78c549c47d4bcd4a726b856013fede6f2ea891
+Subproject commit 60e7e4fa95cbabcd0b6cb8948d90d8ba15e92919