CPLBase64DecodeInPlace() : fix to be robust to malformed base64 strings

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@26536 f0d54148-0727-0410-94bb-9a71ac55c965
Implement reading and writing of ICC profiles in PNG, JPEG and GTiff drivers (patch by cleo, #5246)

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@26537 f0d54148-0727-0410-94bb-9a71ac55c965