Try to fix Windows lld build.

llvm\tools\lld\ELF\MarkLive.cpp(49): error C2872: 'ObjectFile': ambiguous symbol
llvm\tools\lld\elf\InputFiles.h(100): note: could be 'lld::elf::ObjectFile'
llvm\include\llvm/Object/IRObjectFile.h(26): note: or       'llvm::object::ObjectFile'
llvm\tools\lld\ELF\MarkLive.cpp(133): note: see reference to function template instantiation
    'void forEachSuccessor<ELFT>(lld::elf::InputSection<ELFT> *,
                                 std::function<void (lld::elf::InputSectionBase<ELFT> *)>)'
    being compiled with
                [ ELFT=llvm::object::ELF32LE ]
llvm\tools\lld\ELF\MarkLive.cpp(136): note: see reference to function template instantiation
    'void lld::elf::markLive<llvm::object::ELF32LE>(lld::elf::SymbolTable<llvm::object::ELF32LE> *)
    being compiled

llvm-svn: 267161