cpu: introduce and export type CacheLinePad
cpu: introduce and export type CacheLinePad

Add a CacheLinePad struct type that has a size of cacheLineSize.
This can be used for padding structs in order to avoid false sharing.

Fixes golang/go#25203

Change-Id: I6b6daf91ea0e9c50428ffa053035429c3921b461
Reviewed-on: https://go-review.googlesource.com/111775
Run-TryBot: Tobias Klauser <0a68dd4915066ec5d3f81f75a828fee53dcc8822@gmail.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

golang/sys,multiplay/golang-sys,multiplay/golang-sys,multiplay/golang-sys,golang/sys,golang/sys,multiplay/golang-sys