[Bug] Fix buffer-overflow in SetThreadName

[davidmrdavid]

By running msvc's ASan on this project, we detected a buffer-overflow error in RaiseException call in CoreThreadWin's SetThreadName.

See the relevant bit below

void SetThreadName(DWORD dwThreadID, LPCSTR szThreadName)
{
  THREADNAME_INFO info;
  info.dwType = 0x1000;
  info.szName = szThreadName;
  info.dwThreadID = dwThreadID;
  info.dwFlags = 0;

  __try
  {
    // Magic exception which informs the OS of this thread's name
    RaiseException(0x406D1388, 0, sizeof(info)/sizeof(DWORD), (ULONG_PTR*)&info);
  }
  __except(EXCEPTION_CONTINUE_EXECUTION)
  {
  }
}

This method follows the pattern outlined in these docs with one difference, it is dividing sizeof(info) by sizeof(DWORD) instead of sizeof(ULONG_PTR).

This difference is fine for 32-bit architectures (1 pointer = 1 DWORD, or 4 bytes), but not for 64 bit, where 1 pointer is 2 DWORDS (8 bytes).

This PR aims to correct this minor arithmetic error, so it works across all architectures. Thanks!