runtime/internal/atomic: align 64-bit types to 8 bytes everywhere
This change extends https://go.dev/cl/381317 to the
runtime/internal/atomic package in terms of aligning 64-bit types to 8
bytes, even on 32-bit platforms.
Change-Id: Id8c45577d07b256e3144d88b31f201264295cfcd
Reviewed-on: https://go-review.googlesource.com/c/go/+/404096 Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Michael Knyszek <mknyszek@google.com>