Motivation / Problem
Sometime we inadvertently break compilation with MinGW, and it can be unnoticed for a long time (until me or @LordAro happen to try to build with MinGW).
I added MinGW to the CI build (for 32bit and 64bit).
Checklist for review
Some things are not automated, and forgotten often. This list is a reminder for the reviewers.
Wow, takes 13 minutes to run a MingW build .. what is taking so long for this target?
Anyway, still more warnings to fix before we can merge this: https://github.com/OpenTTD/OpenTTD/actions/runs/582953728 :)
Otherwise maybe you can PR the fixes for mingw from this PR, so we can at least accept that?
Adding CI targets that generate warnings isn't that nice, especially as we are currently completely clear of any :) So I guess that would take some more effort to fix/change .. but that doesn't mean we shouldn't already accept the fixes that do work :D