runtime/race: implement race detector for arm64

[zorrorffm]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

Planned for go 1.12

Does this issue reproduce with the latest release?

What operating system and processor architecture are you using (go env)?

arm64 linux

What did you do?

If possible, provide a recipe for reproducing the error.
A complete runnable program is good.
A link on play.golang.org is best.

What did you expect to see?

What did you see instead?

[zorrorffm]

I am going to implement this

[gopherbot]

Change https://golang.org/cl/138675 mentions this issue: cmd/runtime: enable TSAN on arm64