[roll third_party/pigweed] pw_build_info: Switch to pw::span

- Switch from std::span to pw::span.
- Update the custom compilation in build_id_test.py to pull in pw::span
  and its dependencies rather than std::span.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/98263

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 5c9007f0b81d761..d4e68a17b860f9a
Roller-URL: https://ci.chromium.org/b/8811165264507646401
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8811165264507646401
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ib6664ff4001be7332f03d822f4498bd3d258668e
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/98303
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/third_party/pigweed b/third_party/pigweed
index 5c9007f..d4e68a1 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 5c9007f0b81d7612501423c7dcd6594af7312785
+Subproject commit d4e68a17b860f9a7cb52fb5177081975a0f59f51