Make return in memory explicit.

        * function.c (aggregate_value_p): Check DECL_BY_REFERENCE.
        (assign_parm_find_data_types): Remove code for old front end
        invisible reference handling.
        (assign_parms): Handle DECL_BY_REFERENCE on the RESULT_DECL.
        (expand_function_end): Likewise.
        * gimplify.c (gimplify_return_expr): Handle a dereferenced
        RESULT_DECL.
        * tree-inline.c (copy_body_r): Don't bother looking for &* anymore.
        (declare_return_variable): Handle DECL_BY_REFERENCE.
        * cp/cp-gimplify.c (is_invisiref_parm): Also handle RESULT_DECL.
        (cp_genericize_r): Use convert_from_reference.
        Don't dereference a RESULT_DECL directly inside a RETURN_EXPR.
        (cp_genericize): Handle the RESULT_DECL.  Unset TREE_ADDRESSABLE.

From-SVN: r85675