x/sys/unix: missing support for linux/arm64

[minux]

[frobware]

Given that the port was recently merged I was curious as to what "missing support" means. Is this cgo related?

[bradfitz]

@frobware, this is for the x/sys repo (see the github Label on the right).

It's at https://github.com/golang/sys/tree/master/unix

[minux]

Let's keep this issue only about linux/arm64.
The linux/arm issue is different. linux/arm only lacks Syscall9 and a few constants,
whereas unix doesn't support linux/arm64 at all.

[larzconwell]

x/sys/unix supports linux/arm64 as of CL 10038, so this can be closed @minux.