runtime: report finalizer and cleanup queue length with checkfinalizer>0
This change adds tracking for approximate finalizer and cleanup queue
lengths. These lengths are reported once every GC cycle as a single line
printed to stderr when GODEBUG=checkfinalizer>0.
This change lays the groundwork for runtime/metrics metrics to produce
the same values.
For #72948.
For #72950.
Change-Id: I081721238a0fc4c7e5bee2dbaba6cfb4120d1a33
Reviewed-on: https://go-review.googlesource.com/c/go/+/671437 Reviewed-by: Michael Pratt <mpratt@google.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>