tuple structs should generate the same code as structs

[emberian]

Right now tuple structs generate code very similar to/identical to enums. afaict no reason for this.

[pythonesque]

I'm going to take a shot at this.

[thestinger]

@cmr: what exactly do you mean by that?

[emberian]

@thestinger tuple structs are translated as enums, which leads to some ugly IR. I can pull up examples when I have time later in the week if they'd be useful.

[emberian]

Now that we inline enum constructors I think we're golden. My complaints before (but poorly expressed) were that struct fields were getting translated into the proper place but enums were going through calls. Codegen looks good now.