COMP: fix conditional for VTK legacy rendering.

- was deprecated for removal with VTK 8.1.0
  definitely removed in VTK 8.2.0

src/functionObjects/graphics/runTimePostProcessing/runTimePostProcessing.C

@@ -158,8 +158,11 @@ bool Foam::functionObjects::runTimePostProcessing::write()
     auto renderWindow = vtkSmartPointer<vtkRenderWindow>::New();
     renderWindow->OffScreenRenderingOn();
     renderWindow->SetSize(output_.width_, output_.height_);
-    #if (VTK_MAJOR_VERSION < 9)
-    renderWindow->SetAAFrames(10);  // Legacy rendering
+
+    // Legacy rendering - was deprecated for 8.1.0
+    #if (VTK_MAJOR_VERSION < 8) || \
+        ((VTK_MAJOR_VERSION == 8) && (VTK_MINOR_VERSION < 2))
+    renderWindow->SetAAFrames(10);
     #endif
     renderWindow->SetAlphaBitPlanes(true);
     renderWindow->SetMultiSamples(0);