COMP: Update VTK to reference updated Slicer/VTK fork. Issue #3808

Steve changes related to issue #3808 have been integrated into the
Slicer/VTK fork and this commit updates the external project accordingly.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23650 3bd1e089-480b-0410-8dfb-8563597acbee