runtime: add and use runtime/internal/sys.NotInHeap

runtime: add and use runtime/internal/sys.NotInHeap

Updates #46731

Change-Id: Ic2208c8bb639aa1e390be0d62e2bd799ecf20654
Reviewed-on: https://go-review.googlesource.com/c/go/+/421878
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>