(charset_code_point): If CHARSET_CONVERSION is CONVERSION_IDENTICAL,

(charset_code_point): If CHARSET_CONVERSION is CONVERSION_IDENTICAL,
identical conversion is used even if a CCS is ISO-2022 style; instead
of it, CONVERSION_94, CONVERSION_96, CONVERSION_94x94,
CONVERSION_96x96, CONVERSION_94x94x94, CONVERSION_96x96x96,
CONVERSION_94x94x94x94 and CONVERSION_96x96x96x96 are introduced.
(complex_vars_of_mule_charset): Specify CONVERSION_96 instead of
CONVERSION_IDENTICAL for thai-tis620; Specify CONVERSION_94x94 instead
of CONVERSION_IDENTICAL for japanese-jisx0208-1990.