runtime: convert timer.status to atomic type
For #53821
Change-Id: I7cb6a16626964d5023b96609d9921bfe4a679d8f
GitHub-Last-Rev:
ddfce125be4aa565aa4d2081841c649bf2f71459
GitHub-Pull-Request: golang/go#54865
Reviewed-on: https://go-review.googlesource.com/c/go/+/428196
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Jenny Rakoczy <jenny@golang.org>
Auto-Submit: Jenny Rakoczy <jenny@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>