[RyuJIT/arm64] Implement ELT hooks

[BruceForstall]

It looks like genProfilingEnterCallback and genProfilingLeaveCallback will NYI on arm64.

[AndyAyersMS]

@BruceForstall seems like you should take this one?
cc @RussKeldorph

[BruceForstall]

I'll take it, but it's not a 3.0 issue, so I'll move it out of 3.0.

[AndyAyersMS]

Can you comment on why it's not a 3.0 issue?

[BruceForstall]

The diagnostics team does not include the profiling apis for arm64 as a 3.0 committed feature.

[k15tfu]

Hi! Can anyone update Milestone to 5.0?

[BruceForstall]

Why do you want the milestone set to 5.0? It's already been fixed. Nonetheless, I'll do it.

[k15tfu]

5.0 the first version it will be fixed. Just want to specify it explicitly. Thanks