Remove invalid return from void method in vtkIdList

This removes an invalid return statement from the void
IntersectWith() method in the vtkIdList class.

This fixes a compilation error on Win32.

Change-Id: I58a11f4b4469603f56aecad91131f620192e6cdb
Merge topic 'fix-win32-compilation-errors' into master

69509fe0 Remove invalid return from void method in vtkIdList