[PATCH] Ignore/drop visibility for symbols with local linkage

[Rafael Espíndola]

> Weird.  Reattached.  Try again?
>
> Just looking at this again, should the assert be stronger?  I.e., is
> this even better?
>
>     assert(!GlobalValue::isLocalLinkage(LT) &&
>            "Symbols with local linkage should not be merged");
>

The stronger version of the assert LGTM.

Thanks,
Rafael