ENH: build dummy runTimePostProcessing if VTK/ParaView are not available

- this allows more use of the runTimePostProcessing functionObject
  that will fail more gracefully if the proper version could not be
  built.

  The dummy functionObject simply emits a message that it is not available.

src/functionObjects/graphics/runTimePostProcessing/runTimePostProcessing.C

@@ -3,7 +3,7 @@
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
     \\  /    A nd           | Copyright (C) 2015 OpenFOAM Foundation
-     \\/     M anipulation  | Copyright (C) 2015-2016 OpenCFD Ltd.
+     \\/     M anipulation  | Copyright (C) 2015-2018 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -80,12 +80,6 @@ Foam::functionObjects::runTimePostProcessing::runTimePostProcessing
 }
 
 
-// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
-
-Foam::functionObjects::runTimePostProcessing::~runTimePostProcessing()
-{}
-
-
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
 bool Foam::functionObjects::runTimePostProcessing::read(const dictionary& dict)