Static associative array expressions

[Steven Schveighoffer]

On 9/19/21 1:43 AM, Stefan Koch wrote:

> What do you guys think?

I think an easier fix is just to change the call that does the AA 
literals to something that can be CTFEd. Right now it's an extern(C) 
hook that is opaque and takes void[] and TypeInfos.

Something like:

```d
V[K] __aALiteral(V, K)(K[] keys, V[] values);
```

Then just lower the call to that, and if that is CTFEable, it works.

-Steve