[sailfishos][compositor] Make it possible to extend CompositorBridgeP…

…arent

Signed-off-by: Raine Makelainen <raine.makelainen@jolla.com>

gfx/layers/ipc/CompositorBridgeParent.h

@@ -231,7 +231,7 @@ class CompositorBridgeParentBase : public PCompositorBridgeParent,
                           uint32_t aApzcId) override;
 };
 
-class CompositorBridgeParent final : public CompositorBridgeParentBase
+class CompositorBridgeParent : public CompositorBridgeParentBase
                                    , public CompositorController
 {
   friend class CompositorVsyncScheduler;