message: ftp: undef MSVC macro
diff: #if defined(WINDOWS)
  #include "tronkko_dirent.h"
  #include "stackoverflow_unistd.h"
  +// Fix MSVC error C4003
  +// https://stackoverflow.com/a/6884102/8548472
  +#ifdef max
  +#undef max
  +#endif
  #else
  #include <dirent.h>
  #include <unistd.h>
  