The state set is now simplified enough that all the CAS loops
are starting to look the same: they are just spin locks.
So introduce an actual timer.lock method and use it in deltimer.
[This is one CL in a refactoring stack making very small changes
in each step, so that any subtle bugs that we miss can be more
easily pinpointed to a small change.]
Change-Id: Ifd7f20eeede5c764ef10ecba64855c29a5ddbe39
Reviewed-on: https://go-review.googlesource.com/c/go/+/564124 Reviewed-by: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>