[roll third_party/pigweed] pw_transfer: Prevent zero length sleeps on the transfer thread

The transfer thread was ignoring the next timeout and always setting
sleepFor to 0.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/99680

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 84e4983da1c6041..d5b4537fad3a63d
Roller-URL: https://ci.chromium.org/b/8810450883510449617
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8810450883510449617
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I05fd41361fcff8a656ea42b7cd2a5b3bd135651c
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/99722
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 84e4983..d5b4537 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 84e4983da1c60413752fed699388001e97e034d7
+Subproject commit d5b4537fad3a63d43cc76a87d55721ed81bb6b6b