mruby-dir/dirtest.c: should not include <unistd.h>
MODIFY
mrbgems/mruby-dir/test/dirtest.c
mrbgems/mruby-dir/test/dirtest.c
#include <sys/types.h>
#include <sys/stat.h>
-#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define mkdir(path,mode) _mkdir(path)
#define chdir(path) _chdir(path)
#else
+#include <unistd.h>
#include <dirent.h>
#endif

mruby-dir/dirtest.c: should not include <unistd.h>