Skip array embedding if MRB_NO_BOXING and MRB_32BIT; fix #4382

On some platforms, `sizeof(mrb_value) > sizeof(void*)*3`, which makes
`MRB_ARY_EMBED_LEN_MAX` zero. And zero sized array cause compile errors.

src/value_array.h

@@ -6,6 +6,7 @@
 static inline void
 value_move(mrb_value *s1, const mrb_value *s2, size_t n)
 {
+  if (n == 0) return;
   if (s1 > s2 && s1 < s2 + n)
   {
     s1 += n;