BUG: vtkMRMLAnnotationNode: Fix -Wfor-loop-analysis

This commit fixes the following warning:

/path/to/Slicer/Modules/Loadable/Annotations/MRML/vtkMRMLAnnotationNode.cxx:530:20: warning: variables 'id' and 'n' used in loop condition not modified in loop body [-Wfor-loop-analysis]
for (int i = id; id < n-1; i++ )
^~ ~

git-svn-id: http://svn.slicer.org/Slicer4/trunk@25824 3bd1e089-480b-0410-8dfb-8563597acbee