ImportC in a Dub project

[Carsten Schlote]

On Friday, 28 October 2022 at 19:08:47 UTC, Steven Schveighoffer 
wrote:
> By default dub does not build C files (as evidenced by your 
> command line). It may not even let you I don't know, but try:
>
> ```json
>   "sourceFiles" : ["source/zstdc_binding.c"]
> ```

Ok, this works. So Dub is not picking any C files by default. 
Thanks for the hint.

I will spent some time to prepare a fix for Dub, so that C files 
(only '.c' files, no headers) in detected/configured source 
directories are picked up as well.