fix list destructors

c_os/user/lib/ArrayList.h

@@ -120,7 +120,7 @@ private:
     }
 
 public:
-    ~ArrayList() override {
+    ~ArrayList() {
         delete[] buf;  // Deleting nullptr has no effect
     }
 

c_os/user/lib/LinkedList.h

@@ -65,7 +65,7 @@ private:
     }
 
 public:
-    ~LinkedList() override {
+    ~LinkedList() {
         typename Iterator::Type* current = head;
         typename Iterator::Type* next;
 

c_os/user/lib/List.h

@@ -9,8 +9,6 @@
 template<typename T, typename I = Iterator<T>>
 class List {
 public:
-    virtual ~List() = 0;
-
     using Type = T;      // We make the template argument accessible from the subclasses
     using Iterator = I;  // Needed for range based for loop