Update _insert prototype of array to match list _insert.

tests/test-marray.c

@@ -275,7 +275,7 @@ static void test_d(void)
   array_uint_it_set (it2, it);
   assert (array_uint_it_equal_p(it2, it));
   assert (*array_uint_ref(it2) == 0);
-  array_uint_insert(it2, 17);
+  array_uint_insert(a1, it2, 17);
   assert (array_uint_size(a1) == 300);
   
   array_uint_init_set (a2, a1);