[roll pigweed] pw_span: Remove implicit polyfill from GN

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/99640

https://pigweed.googlesource.com/pigweed/pigweed
pigweed Rolled-Commits: 08e18e565058e06..ac3ca982d7f86f4
Roller-URL: https://ci.chromium.org/b/8810004780163290753
Cq-Cl-Tag: roller-builder:pigweed-zephyr-roller
Cq-Cl-Tag: roller-bid:8810004780163290753
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I365e85a87bfa079e09ba4b8ef7bbbad3fdc3c751
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/zephyr-integration/+/100401
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 08e18e5..ac3ca98 160000
--- a/pigweed
+++ b/pigweed
@@ -1 +1 @@
-Subproject commit 08e18e565058e06352c364a927af4eab438ed22a
+Subproject commit ac3ca982d7f86f4d6e18b81f4ee67d85918cf90f