message: Fix mac build broken in r316987
  Forgot one occurence of ArchSpec::SetTriple in mac-specific code.
diff: @@ -468,7 +468,7 @@ Status ProcessMachCore::DoLoadCore() {
  // it to match the core file which is always single arch.
  ArchSpec arch(m_core_module_sp->GetArchitecture());
  if (arch.GetCore() == ArchSpec::eCore_x86_32_i486) {
  - arch.SetTriple("i386", GetTarget().GetPlatform().get());
  + arch = Platform::GetAugmentedArchSpec(GetTarget().GetPlatform().get(), "i386");
  }
  if (arch.IsValid())
  GetTarget().SetArchitecture(arch);
  