cpu: define cacheLineSize and doinit for WASM
cpu: define cacheLineSize and doinit for WASM

This fixes a build break when compiling this package with
GOOS=js / GOARCH=wasm.

Updates golang/go#30241

Change-Id: I0b35aa50a69370ed0d83c522e12ce7613c4c3ec4
Reviewed-on: https://go-review.googlesource.com/c/sys/+/165749
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

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