fix nano5g support
fix nano5g support

It was broken when adding hashAB support because even if the
nano5g says it uses DBVersion 3, it expects Locations.itdb.cbk to
be checksummed using a hash72 (as if it was a DBVersion 4 device).

hyperair/libgpod,neuschaefer/libgpod,hyperair/libgpod,hyperair/libgpod,hyperair/libgpod,neuschaefer/libgpod,neuschaefer/libgpod,neuschaefer/libgpod,hyperair/libgpod,neuschaefer/libgpod