(Vstandard_character_unification_table_for_decode):

(Vstandard_character_unification_table_for_decode):
Name changed from Vstandard_character_unification_table_for_read.
(Vstandard_character_unification_table_for_encode): Name changed
from Vstandard_character_unification_table_for_write.
(Qcharacter_unification_table_for_decode): New variable.
(Qcharacter_unification_table_for_encode): New variable.
(decode_coding_iso2022): Adjusted for the above name change.
(encode_coding_iso2022): Likewise.
(ENCODE_ISO_CHARACTER): Bug of handling return value of unify_char
fixed.
(DECODE_SJIS_BIG5_CHARACTER): New macro.
(decode_coding_sjis_big5): Handle character unificatoin table.
Use macro DECODE_SJIS_BIG5_CHARACTER.
(encode_coding_sjis_big5): Handle character unificatoin table.
Use macro ENCODE_SJIS_BIG5_CHARACTER.
(setup_coding_system): Handle members
character_unification_table_for_decode and
character_unification_table_for_encode of the variable coding.
(Ffind_operation_coding_system): Renamed from Ffind_coding_system.
(syms_of_coding): Initialize and staticpro
Qcharacter_unification_table_for_decode and
Qcharacter_unification_table_for_decode.  Declare
Ffind_operation_coding_system as Lisp functions.  Declare
Vstandard_character_unification_table_for_decode and
Vstandard_character_unification_table_for_encode as Lisp
variables.