[roll third_party/pigweed] pw_hdlc: Multibyte address support

This extends the HDLC encoder and decoder in both C++ and Python to use
HDLC extended addressing, where the address field is a one-terminated
LSB varint.

Classes using HDLC, such as the HDLC ChannelOutput and WirePacketParser,
are updated accordingly.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/38020

third_party/pigweed Rolled-Commits: 2f56efcee319268..b9fda58850ddab0
Roller-URL: https://ci.chromium.org/b/8852307227775816928
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8852307227775816928
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I675d07113950f67c9fe8f4a1cb0c895251405a7e
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/38684
Reviewed-by: 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 2f56efc..b9fda58 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 2f56efcee3192685898200f6049538ebd809ae36
+Subproject commit b9fda58850ddab067bb271c2daacbbfabf57de58