cmake VTK_HAVE_XCURSOR examples

Kitware/VTK Rendering/OpenGL2/CMakeLists.txt :456

set_property(SOURCE vtkXOpenGLRenderWindow.cxx APPEND
    PROPERTY
      COMPILE_DEFINITIONS "VTK_HAVE_XCURSOR=$<TARGET_EXISTS:X11::Xcursor>"
  )

Kitware/VTK Rendering/WebGPU/CMakeLists.txt :265

set_property(SOURCE vtkXWebGPURenderWindow.cxx APPEND
      PROPERTY
        COMPILE_DEFINITIONS "VTK_HAVE_XCURSOR=$<TARGET_EXISTS:X11::Xcursor>"
    )