A new demangler test?

[Vincent Povirk]

While this may be a useful exercise (and I'd personally like to see
some demangler improvements, particularly support for managed
references), this sort of broad test doesn't make sense for the Wine
test suite, especially if we can't be sure it will always work on
Windows. It's the sort of thing you could use to detect problems with
our code, which you could then add a few individual tests for.

Maybe it could be added to winezeug? Or is there a more appropriate place?