mastic: Add additional test vectors (#1184)

* MasticCount_2.json uses an aggregation parameter that is sensitive to
  the order in which the nodes are visited during the eval proof
  traversal.

* MasticCount_3.json uses an aggregation parameter that excludes the weight
  check.

src/vdaf/mastic.rs

@@ -1565,6 +1565,24 @@ mod tests {
             );
         }
 
+        #[test]
+        fn count_2() {
+            check_test_vec(
+                0xFFFF0001,
+                |_type_params| Count::<Field64>::new(),
+                include_str!("test_vec/mastic/04/MasticCount_2.json"),
+            );
+        }
+
+        #[test]
+        fn count_3() {
+            check_test_vec(
+                0xFFFF0001,
+                |_type_params| Count::<Field64>::new(),
+                include_str!("test_vec/mastic/04/MasticCount_3.json"),
+            );
+        }
+
         #[test]
         fn sum_0() {
             check_test_vec(