'make paraview' does not perform incremental builds when `paraview_SOURCE_SELECTION` is set to `source`

Incremental builds of ParaView with 'make paraview' are not executed when paraview_SOURCE_SELECTION is set to source and code in the source directory is modified. Incremental builds are executed with 'make paraview' when paraview_SOURCE_SELECTION is set to git.

From @wascott:

Here is what I did with an existing superbuild:

in the Source directory, touch ParaViewCore/ClientServerCore/Rendering/vtkPVRenderingCapabilitiesInformation.cxx
in the highest level build directory,
make (nothing got rebuilt)
make paraview (nothing got rebuilt)
cd superbuild/paraview/build
make (Now, this worked.  Still rebuilding anything that was affected.)
make install
cd ../../../
make (does nothing, as expected)
make install (now, lots of stuff gets installed).

'make paraview' should work consistently across the different options for paraview_SOURCE_SELECTION.

cc: @ben.boeckel