message: [RegisterContextDarwin_arm64] Include the headers for getsysctlbyname.
  This code is only used under __arm64__, use the correct guard.
  <rdar://problem/55916729>
diff: #include <memory>
  +#if defined(__APPLE__) && (defined(__arm64__) || defined(__aarch64__))
  +#include <sys/types.h>
  +#include <sys/sysctl.h>
  +#endif
  +
  // Support building against older versions of LLVM, this macro was added
  // recently.
  #ifndef LLVM_EXTENSION
  