(Qto_decomposition_at_compat): Deleted.

(Qto_decomposition_at_compat): Deleted.
(Qto_decomposition_at_superscript): New variable.
(put_char_composition): Use `=>decomposition@superscript' instead of
`=decomposition' for compatibility decomposition mapping tagged
`super'.
(Fput_char_attribute): Fix condition about `put_char_composition'.
(syms_of_chartab): Delete builtin symbol `=>decomposition@compat'; add
news symbol `=>decomposition@superscript'.