Post process elfdump data retrieved from the database to transform List into namedtuple

Here is the only remaining patch since you fixed the others in the meantime.

From the commit message:

json doesn't preserve the namedtuple, they are translated to list.
So we must post process the json data to transform them back into
namedtuple.
    
The function was already present but not activated. This patch also
removes the function from ElfExtractor to put it directly in checkpkg_lib
to remove a dependency.