r203052 - Construct GlobalValues with the correct linkage instead of using setLinkage.

[Rafael Espíndola]

>> BTW, what is the interaction of N_NO_DEAD_STRIP and S_ATTR_NO_DEAD_STRIP?
>
> N_NO_DEAD_STRIP applies to individual symbols.
> S_ATTR_NO_DEAD_STRIP applies to everything in a section.
>
> The linker ORs the two together to decided if an atom is must not be dead stripped.

OK, thanks.

Just one more question. When doing LTO, what will ld64 tell us about
these symbols? Will it say that they are required and that llvm should
not hide them? I ask because the other issue I would like to sort is
shouldEmitUsedDirectiveFor. If ld64 tells llvm to keep the symbols, we
only need to put the private symbols in llvm.compiler.used. If we are
not told to keep them, then they the weak symbols have to go to
llvm.compiler.used too.

Cheers,
Rafael