Stop keeping a Path.t to refer to labels and constructors in the Typedtree AST.  This is not used internally and it is not a robust way to identify these objects unambiguously anyway
    (especially when we will add more powerful disambiguation strategies).  The correct way to identify an item is through the pair (type,name), which can be deduced from the
    label_description/constructor_description stored in the Typedtree.
    
    
    
    git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@13043 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02