[lld] r275258 - Reverted r275257 "[ELF] - Implement extern "c++" version script tag"

[Rafael Espíndola via llvm-commits]

> What would be a solution for lld ?
> I have concerns about windows users. While we are stick to linux libs
> we can't support them. I think until now and issues with zlib lld was crossplatform linker.
> And we probably want to have a solution for that.

I think the only real solution is to have a c++ demangler in llvm.

For now what we can do is make the cmake check stricter and add a
"REQUIRES: demangler" to the tests.

Cheers,
Rafael