message: Fix building with the Windows 8.1 SDK
  Windows 8.1 didn't support ARM64
diff: @@ -122,9 +122,11 @@ void util::get_platform_info(PlatformInfo& info)
  case PROCESSOR_ARCHITECTURE_ARM:
  info_2.machine = "arm"; // Throws
  break;
  +#if defined(PROCESSOR_ARCHITECTURE_ARM64)
  case PROCESSOR_ARCHITECTURE_ARM64:
  info_2.machine = "arm64"; // Throws
  break;
  +#endif
  case PROCESSOR_ARCHITECTURE_INTEL:
  info_2.machine = "x86"; // Throws
  break;
  