message: mavlink_ftp: fix the unistd.h include again
diff: #if defined(WINDOWS)
  #include "tronkko_dirent.h"
  +#include "stackoverflow_unistd.h"
  #include <direct.h>
  #define mkdir(D, M) _mkdir(D)
  #else
  #include <dirent.h>
  +#include <unistd.h>
  #endif
  +
  #include <fcntl.h>
  #include <sys/types.h>
  #include <sys/stat.h>
  #include <stack>
  #include <stdio.h>
  -#include <unistd.h>
  #include "fs.h"
  