COMP: Fix "unused-local"typedefs" warning and update ITKv4

Commit r23121 removed the addition of "-Wno-unused-local-typedefs",
this commit is an attempt to clean most of the warnings. It also
updates the ITKv4 external project so that it checks out the Slicer ITK
fork including the ITK patch currently in review. See [1], [2]

$ git shortlog 01661ccf99..184b1257ad
Jean-Christophe Fillion-Robin (3):
      COMP: Properly fix unused-local-typedefs warning using unused attribute.
      COMP: Fix "unused-local-typedefs" warnings
      COMP: Backport double conversion fix for "unused-local-typedefs" warning

[1] http://review.source.kitware.com/#/c/15379/
[2] http://review.source.kitware.com/#/c/15380/

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23140 3bd1e089-480b-0410-8dfb-8563597acbee