Get rid of exclude-list for Windows-only tests Main purpose of this change is to get rid of a quite long (and growing) list of excluded targets, while this test should only be useful on Windows (as far as I understand it). The `// only-windows` header seams to implement exactly what we need here. I don't know why there are some whitespace changes, but `x.py fmt` and `.git/hooks/pre-push` are happy.