[patch] Fix linkage computation for derived types in inline functions

[Rafael Espíndola]

> Yes. InternalLinkage + VisibleNoLinkage is externally visible under those
> merging rules, and shouldn't be.
>
> Also, this doesn't match what I thought we were going to do to resolve that
> DR (that you take the weakest linkage of a template and its arguments for a
> template specialization). Why do you think these revised rules are better?
> What's your model?

By revised rules you mean the one you proposed, making

InternalLinkage        VisibleNoLinkage       -> NoLinkage
UniqueExternalLinkage  VisibleNoLinkage       -> NoLinkage

I am OK with it, but I was unable to write any testcase :-(

Cheers,
Rafael