Add a "fork" of musl as //fusl.

fusl/src/dirent/readdir.c

+#include <dirent.h>
+#include <errno.h>
+#include "__dirent.h"
+#include "syscall.h"
+#include "libc.h"
+
+int __getdents(int, struct dirent *, size_t);
+
+struct dirent *readdir(DIR *dir)
+{
+        struct dirent *de;
+        
+        if (dir->buf_pos >= dir->buf_end) {
+                int len = __syscall(SYS_getdents, dir->fd, dir->buf, sizeof dir->buf);
+                if (len <= 0) {
+                        if (len < 0 && len != -ENOENT) errno = -len;
+                        return 0;
+                }
+                dir->buf_end = len;
+                dir->buf_pos = 0;
+        }
+        de = (void *)(dir->buf + dir->buf_pos);
+        dir->buf_pos += de->d_reclen;
+        dir->tell = de->d_off;
+        return de;
+}
+
+LFS64(readdir);