fix for netcdf driver cannot read netcdf-4 files with UBYTE data (#5053)

git-svn-id: https://svn.osgeo.org/gdal/trunk@25919 f0d54148-0727-0410-94bb-9a71ac55c965
add autotests for #5053

git-svn-id: https://svn.osgeo.org/gdal/trunk@25920 f0d54148-0727-0410-94bb-9a71ac55c965