Refactor X86 symbol access classification

[Rafael Espíndola via llvm-commits]

On 20 May 2016 at 11:18, Mehdi Amini <mehdi.amini at apple.com> wrote:
> +                                 const Module &M, const GlobalValue *GV) {
> +  // DLLImport explicitly marks the GV as external.
> +  if (GV && GV->hasDLLImportStorageClass())
> +    return false;
>
>
> Do we need to accept nullptr GV? Can it be a reference?

Yes, we do. For ExternalSymbols we don't have a GV.

Cheers,
Rafael