Fix -Wdelete-non-abstract-non-virtual-dtor warning

src/msw/graphicsd2d.cpp

@@ -390,6 +390,10 @@ public:
     {
     }
 
+    virtual ~wxDirect2DFontFileEnumerator()
+    {
+    }
+
     // IDWriteFontFileEnumerator methods
     virtual wxSTDMETHODIMP MoveNext(BOOL* pHasCurrentFile) wxOVERRIDE
     {
@@ -449,6 +453,10 @@ public:
         ms_isInitialized = true;
     }
 
+    virtual ~wxDirect2DFontCollectionLoader()
+    {
+    }
+
     // IDWriteFontCollectionLoader methods
     virtual wxSTDMETHODIMP CreateEnumeratorFromKey(IDWriteFactory* pFactory,
                                         void const* pCollectionKey, UINT32 collectionKeySize,