ENH: Deprecate the vtkPolynomialSolversUnivariate in vtkMath.

The API is duplicated, and should be removed from vtkMath entirely in a
future release.

Change-Id: I584f0a1d828dafd3a5d98c98f1177642bbba28d3

VolumeRendering/vtkVolumeRayCastIsosurfaceFunction.cxx

@@ -17,6 +17,7 @@
 #include "vtkCamera.h"
 #include "vtkColorTransferFunction.h"
 #include "vtkMath.h"
+#include "vtkPolynomialSolversUnivariate.h"
 #include "vtkObjectFactory.h"
 #include "vtkPiecewiseFunction.h"
 #include "vtkRenderWindow.h"