Remove virtual inheritance from RendererOpenGL

Also make destructor virtual so that instances are properly destructed.

src/video_core/renderer_base.h

@@ -19,7 +19,7 @@ public:
     RendererBase() : m_current_fps(0), m_current_frame(0) {
     }
 
-    ~RendererBase() {
+    virtual ~RendererBase() {
     }
 
     /// Swap buffers (render frame)

src/video_core/renderer_opengl/renderer_opengl.h

@@ -13,11 +13,11 @@
 
 #include <array>
 
-class RendererOpenGL : virtual public RendererBase {
+class RendererOpenGL : public RendererBase {
 public:
 
     RendererOpenGL();
-    ~RendererOpenGL();
+    ~RendererOpenGL() override;
 
     /// Swap buffers (render frame)
     void SwapBuffers();