[roll third_party/pigweed] pw_rpc: Fix size report

An API change broke the pw_rpc size reports.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/110471

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: cd52bad9aa4cbb0..399048cf646a472
Roller-URL: https://ci.chromium.org/b/8802919682551961729
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I44caf29fe7a43f0f5a319b5eafe431be7132e692
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/110516
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 cd52bad..399048c 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit cd52bad9aa4cbb0b9d94415d7be0917138e285d8
+Subproject commit 399048cf646a472f039488cec670268772c24b1a