[roll pigweed] pw_toolchain: CIPD-provided sysroot on CMake/Linux

Changes the host clang CMake toolchain to use the CIPD-provided sysroots
when building for Linux.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/106170

https://pigweed.googlesource.com/pigweed/pigweed
pigweed Rolled-Commits: 350885153202b98..7f2f5e0c147ef49
Roller-URL: https://ci.chromium.org/b/8804931526760296545
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ied4ea1dd938cb00b799778673a4df513e9221e6a
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/zephyr-integration/+/108060
Bot-Commit: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/pigweed b/pigweed
index 3508851..7f2f5e0 160000
--- a/pigweed
+++ b/pigweed
@@ -1 +1 @@
-Subproject commit 350885153202b986133b27f41d468f8ad41b42e3
+Subproject commit 7f2f5e0c147ef49de1094f40d3952ad51981b5bc