Default, use hash function in the runtime package.
If the build tag is purego or raw memory cannot be hash directly,
use reflect get each field to hash separately.
Fixes#54670
Change-Id: Ic968864c9c3c51883967d4f6dc24432385c7dc79
GitHub-Last-Rev: 5ae8a28834
GitHub-Pull-Request: golang/go#69166
Reviewed-on: https://go-review.googlesource.com/c/go/+/609761
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
