(ONE_MORE_BYTE_NO_CHECK): Increment consumed_chars.

(ONE_MORE_BYTE_NO_CHECK): Increment consumed_chars.
(emacs_mule_char): New arg src.  Delete arg `composition'.  Caller
changed.  Handle 2-byte and 3-byte charsets correctly.
(DECODE_EMACS_MULE_COMPOSITION_RULE_20): Renamed from
DECODE_EMACS_MULE_COMPOSITION_RULE.  Caller changed.
(DECODE_EMACS_MULE_COMPOSITION_RULE_21): New macro.
(DECODE_EMACS_MULE_21_COMPOSITION): Call
DECODE_EMACS_MULE_COMPOSITION_RULE_21.  Produce correct annotation
sequence.
(decode_coding_emacs_mule): Handle composition correctly.  Rewind
`src' and `consumed_chars' correctly before calling
emacs_mule_char.
(DECODE_COMPOSITION_START): Correctly handle the case of altchar
and alt&rule composition.
(decode_coding_iso_2022): Handle composition correctly.
(init_coding_once): Setup emacs_mule_bytes for private charsets.