To unsure fvOptions are instantiated for post-processing createFvOptions.H must
be included in createFields.H rather than in the solver directly.
Resolves bug-report https://bugs.openfoam.org/view.php?id=2733
BUG: porousSimpleFoam: moved createFvOptions.H into createFields.H for -postProcess option
Resolves bug-report https://bugs.openfoam.org/view.php?id=2733
BUG: solvers: Moved fvOption construction into createFields.H for post-processing
This ensures that the fvOptions are constructed for the -postProcessing option
so that functionObjects which process fvOption data operate correctly in this
mode.