C style callbacks fix for member callbacks

[IntegratedDimensions]

On Monday, 21 May 2018 at 02:23:27 UTC, ag0aep6g wrote:
>> I tried this. Your code crashes in windows dmd x86 x64.
>
> Hm. Works for me in a virtual machine. But I'm not surprised 
> that it's fragile. It might be completely wrong, and it just 
> happens to look alright on my machine.

https://run.dlang.io/is/CMNnJY

Shows the static version produces the same code as the 
non-static. The code was probably compiled on linux.

I can't tell though on my machine what is going on since I cannot 
disassemble properly and what I do see is far more complex.