Add ImportC compiler to dmd

[Markk]

On Monday, 10 May 2021 at 09:27:35 UTC, Walter Bright wrote:

> Since this is all front end work, and it translates the C code 
> into D AST nodes, it should "just work".

With that crucial information added it suddenly made perfect 
sense to me.

Brilliant!

> After all, CTFE "just worked" with ImportC. I didn't do a thing 
> to enable it. I didn't do a thing to the glue code, optimizer, 
> or back end (other than not generating moduleinfo).

How are modules defined? I mean, how do you import and 
symbol-reference it from D?

Assuming everything `extern` in C needs to be in the same 
module/namespace?

_Mark