ENH: Update ITK cherry-picking "BridgeOpenCV" and "CentOS build" fixes

$ git shortlog 51760b2..619f991 --no-merges
Matthew McCormick (2):
ENH: Allow ITKVideoBridgeOpenCV to be built externally.
COMP: Add export specification for itk::ResourceProbe.

Sean McBride (1):
DOC: Update some woefully out-of-date GDCM comments, and typos

Seun Odutola (1):
BUG: Improved itkAnalyzeImageIO to handle case insensitive extensions

git-svn-id: http://svn.slicer.org/Slicer4/trunk@24864 3bd1e089-480b-0410-8dfb-8563597acbee