fix(common): Add virtual destructor for Tool class

Signed-off-by: Philipp Jungkamp <philipp.jungkamp@rwth-aachen.de>

Author: pjungkamp

common/include/villas/tool.hpp

@@ -48,6 +48,8 @@ class Tool {
   virtual void parse() {}
 
   virtual int run();
+
+  virtual ~Tool() {}
 };
 
 } // namespace villas