Pass 'with-gcc:' specified compiler to 'stack setup', fixes #5493

[hasufell]

@BebeSparkelSparkel

[hasufell]

Can this be merged?

[nh2]

This looks correct to me.

[hasufell]

@mpilgrem

[mpilgrem]

Thanks! As a Windows user, it took me a little while to work through this, but it also looked correct to me. I have merged it. However, I did make the following changes. Like @dpwiz, I found doing a lot in a single line a bit 'concentrated', despite @hasufell's helpful explanation here. I took things step by step. (I noted that the rio package, on which Stack depends, does not provide views.) I added a couple of comments, essentially to capture things I had to look up to understand the algorithm. Finally, I updated the ChangeLog.md.