WRG: fix warnings declaration shadows a previous local seen with gcc 8

Fix most of the 39 warnings on pc-christophe (gcc 8):

https://dash.orfeo-toolbox.org/viewBuildError.php?type=1&buildid=332827

I've tagged the MR as 'patch' but also register the branch to the test queue to check if I did not forget any fixable warnings.

Modules/Detection/ObjectDetection/include/otbDescriptorsListSampleGenerator.h

@@ -183,7 +183,6 @@ private:
 
   bool IsInsideWithNeighborhoodRadius(const RegionType& region, const ContinuousIndexType &index) const
     {
-    typedef typename RegionType::IndexType     IndexType;
     typedef typename IndexType::IndexValueType IndexValueType;
     typedef typename ContinuousIndexType::ValueType ContinuousIndexValueType;