reimplement Q_DISABLE_COPY_MOVE for full compatibility with versions < 5.13

I was under the impression Q_DISABLE_COPY_MOVE was a much older function than
it is. Since we historically target 5.6 and these functions are small
convenience functions, I just implemented them in the actual codebase.

app/render/backend/renderbackend.h

@@ -3,6 +3,7 @@
 
 #include <QLinkedList>
 
+#include "common/constructors.h"
 #include "decodercache.h"
 #include "node/graph.h"
 #include "node/output/viewer/viewer.h"
@@ -14,7 +15,7 @@ class RenderBackend : public QObject
 public:
   RenderBackend(QObject* parent = nullptr);
 
-  Q_DISABLE_COPY_MOVE(RenderBackend)
+  DISABLE_COPY_MOVE(RenderBackend)
 
   bool Init();