[roll third_party/pigweed] pw_ide: Fix for clang installed to project dir

If pigweed based project specify clang dependency in its own package
json file. The clang toolchain will be installed to a location different
from $PW_PIGWEED_CIPD_INSTALL_DIR.
In that case, `pw ide` needs to be aware of the clang toolchain path for
clangd itself and its query drivers.

Tried having "fuchsia/third_party/clang/" in project's package file and
removing it. Verified `pw ide sync` works in both cases.

Original-Bug: 314693384
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/184010

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 3c8f177961affcb..8616c571bcec99c
Roller-URL: https://ci.chromium.org/b/8761943145636059713
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I5fe9c7de963077b62e74d6ae189e8203366969f4
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/184710
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 3c8f177..8616c57 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 3c8f177961affcba1a1415fa99c3b8e590aa8e3e
+Subproject commit 8616c571bcec99c28746e49d87754d3972030913