[dmd-internals] Destructors are not virutal

[Daniel Murphy]

Update:
I've patched dmd to link with c++ static member functions, non-virtual
member functions, constructors, destructors, template structs and
classes, and static variables. (windows only)

If anyone wants to try it out (and send me test cases!) it's here:
https://github.com/yebblies/dmd/compare/master...cpplink4
I'd be especially please with comments from anybody that understands
the glue/backend about what I've done wrong - a lot of it was
guesswork.

I consider it 'barely tested'.