[roll third_party/pigweed] pw_allocator: Add AllocationTestHarness

This CL adds a test utility class that can generate requests to
allocate, deallocate, and reallocate memory. The class has a
configurable number of allocated pointers it can record in a vector.
Finally, this class has methods to handle these requests that can be
used to programatically drive the allocator with a large number of
generated calls as part of a fuzz, perf, and/or stress test.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/180532

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 44287c6af439945..7dde8e8f4926d8d
Roller-URL: https://ci.chromium.org/b/8763066338250016977
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ida58394f9793d2bd56419fe19600e07cec0e3956
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/183012
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 44287c6..7dde8e8 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 44287c6af4399458f40315706157192e87fb9ace
+Subproject commit 7dde8e8f4926d8da302de284884e3a568b8015ed