[roll third_party/pigweed] pw_unit_test: Provide start_time to ResultDB

This will be useful for time-limiting queries.

Original-Bug: 247857184
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/112316

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: bcf38c3a86fb97b..99c5463d2c830d2
Roller-URL: https://ci.chromium.org/b/8801755006037189185
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I62bc09012e2c042a7b9532c18dc8eec3b98abfa8
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/112433
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 bcf38c3..99c5463 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit bcf38c3a86fb97bcb825e8ab7ea91fe3ea6180e2
+Subproject commit 99c5463d2c830d2bb05136c76081f3166a6c68ab