(Q_same): New variable.

(Q_same): New variable.
(Q_same_of): New variable.
(Fput_char_attribute): Convert char-refs in value of `{->|<-}same' to
characters and put reverse links.
(Fsave_char_attribute_table): Use `Fchar_refs_simplify_char_specs' for
`{->|<-}same'.
(syms_of_chartab): Add new symbols `{->|<-}same'.