tor-cell: Rename fixed_len to fixed_len_handshake
This commit renames the fixed_len! macro to fixed_len_handshake!, in order to indicate, that this macro is only suited for cells with commands related to handshaking.
This commit renames the fixed_len! macro to fixed_len_handshake!, in order to indicate, that this macro is only suited for cells with commands related to handshaking.