[roll third_party/pigweed] pw_sync: adds VirtualBasicLockable interface

Adds a virtual lock interface in case the lock selection cannot
be templated.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/58202

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 3787c625ef60d64..baf2fdc34ff37cf
Roller-URL: https://ci.chromium.org/b/8836450255218314049
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8836450255218314049
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I712baad37bbc5af27f3832249ce866254fc91871
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/60485
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 3787c62..baf2fdc 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 3787c625ef60d64e8017ff2d4e212a87be150dff
+Subproject commit baf2fdc34ff37cf6e33dd4016c125549cbd66e2c