Test JPEG optimized RasterIO

git-svn-id: https://svn.osgeo.org/gdal/trunk@28034 f0d54148-0727-0410-94bb-9a71ac55c965
PNG: add optimized dataset RasterIO()

git-svn-id: https://svn.osgeo.org/gdal/trunk@28035 f0d54148-0727-0410-94bb-9a71ac55c965
Merge branch 'trunk' into trunk_travis_macosx