Add explicit virtual default destructors

We need to silence the warning about this because Steinberg doesn't
declare their base class destructors as virtual (because of Windows ABI
compatibility issues). But we can still do it inside of yabridge to have
at least a bit more safety.

src/common/communication/vst2.h

@@ -31,7 +31,7 @@
  */
 class DefaultDataConverter {
    public:
-    virtual ~DefaultDataConverter() noexcept;
+    virtual ~DefaultDataConverter() noexcept = default;
 
     /**
      * Read data from the `data` void pointer into a an `Vst2Event::Payload`