[llvm] r239921 - Allow aliases to be unnamed.

[Rafael Espíndola]

>> If globals can be unnamed, there is no reason for aliases to be different.
>
>
> Hold on. What is an alias except a second name for the same object? How
> would you lower an unnamed alias to any object format?

Right now on the same silly way we lower globals:

@0 = global i32 0
@1 = alias i32* @0

produces

__unnamed_1:
...
__unnamed_2 = __unnamed_1

We should really restrict unnamed GVs to have internal or private
linkage. With that we could even hope to lower them to unnamed symbol,
but that is independent.

Cheers,
Rafael