message: mavlink_ftp: unistd.h is not available on Windows
diff: #if defined(WINDOWS)
  #include "tronkko_dirent.h"
  +#include <io.h>
  #else
  #include <dirent.h>
  +#include <unistd.h>
  #endif
  #include <fcntl.h>
  #include <sys/stat.h>
  -#include <unistd.h>
  +
  #include "crc32.h"
  #include "fs.h"
  