[PATCH] D13345: [ELF2] Add --undefined option

[Rafael Espíndola via llvm-commits]

> It is OK for now. We don't do multi-threading soon. We probably want to have a init() function for each file which initialize static members. We can do that later.

It should be possible to statically initialize this somehow, but need
to look deeper a bit on why just

template <class ELFT>
typename DefinedAbsolute<ELFT>::Elf_Sym
DefinedAbsolute<ELFT>::IgnoreUndef = {0, 0, ..., 2, 0... };

Doesn't compile.

Cheers,
Rafael