Added a missing dependency for vtkParaViewWebCore

Not sure why this worked with OpenGL, but not OpenGL2, it may be
some of the paired down dependencies in vtkIOExport. Adding this
dependency explicitly.

Change-Id: I29527513718f9b62d018cfb3bf382e0880412b81
Merge topic 'pvweb-opengl2' into next

10ac0cc9 Added a missing dependency for vtkParaViewWebCore