runtime: use max/min func
Change-Id: I3f0b7209621b39cee69566a5cc95e4343b4f1f20
GitHub-Last-Rev:
af9dbbe69ad74e8c210254dafa260a886b690853
GitHub-Pull-Request: golang/go#63321
Reviewed-on: https://go-review.googlesource.com/c/go/+/531916
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Mauri de Souza Meneguzzo <mauri870@gmail.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Keith Randall <khr@golang.org>