[roll third_party/pigweed] pw_allocator: Doxygenify the remaining Block functions

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/151270

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: ef8c7d6d0c16f50..5e765ab48d6bb16
Roller-URL: https://ci.chromium.org/b/8778368752149759313
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I1fd041fef2436ef1fd07e2eec559002eea97645f
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/151693
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Bot-Commit: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index ef8c7d6..5e765ab 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit ef8c7d6d0c16f50fdc1e75201b8e418aac9f07da
+Subproject commit 5e765ab48d6bb1693421039cfbe8a2e3f0f22807