GTiff internal overviews: for near, average, gauss and cubic, and pixel interleaving, make sure to use the same code path for compressed vs uncompressed overviews (#5701)

git-svn-id: https://svn.osgeo.org/gdal/trunk@27876 f0d54148-0727-0410-94bb-9a71ac55c965
Merge branch 'trunk' into trunk_vc12