[roll third_party/pigweed] pw_multibuf: Add soong support

- Add rules to build pw_multibuf libraries.
- Fix missing headers to existing libraries.

Test: (Needs android checkout) `m pw_multibuf`

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/186815

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 33ff80f6cc3c02a..4559b52b5d2f564
Roller-URL: https://ci.chromium.org/b/8759799651576489089
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I75f3444d2ed044a22f013edb71ed39087856b811
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/186799
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 33ff80f..4559b52 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 33ff80f6cc3c02a1c2c5ce0a69e0229f1f0691c2
+Subproject commit 4559b52b5d2f564949e8a99b5e6d94458101b0a8