[lldb/Interpreter] Pacify -Wnon-virtual-dtor

Author: d0k

lldb/unittests/Interpreter/TestOptionValue.cpp

@@ -14,6 +14,7 @@ using namespace lldb_private;
 
 class Callback {
 public:
+  virtual ~Callback() = default;
   virtual void Invoke() const {}
   void operator()() const { Invoke(); }
 };