(Qsafe_charsets): This variable deleted.

(Qsafe_charsets): This variable deleted.
(Qsafe_chars, Vchar_coding_system_table, Qchar_coding_system): New
variables.
(coding_safe_chars): New function.
(CODING_SAFE_CHAR_P): New macro.
(CHARSET_OK): New arg C.  Call CODING_SAFE_CHAR_P instead of
checking safe_charsets member of the coding system.  Caller
changed.
(detect_coding_iso2022): New local variable safe_chars.
(DECODE_DESIGNATION): Call CODING_SAFE_CHAR_P instead of checking
safe_charsets member of the coding system.
(decode_coding_iso2022): New local variable safe_chars.
(ENCODE_ISO_CHARACTER_DIMENSION1): Don't check unsafe chars here.
(ENCODE_ISO_CHARACTER_DIMENSION2): Likewise.
(ENCODE_ISO_CHARACTER): Arguments changed.  Caller changed.
(ENCODE_UNSAFE_CHARACTER): New macro.
(encode_coding_iso2022): New local variable safe_chars.  Check
unsafe chars.
(setup_coding_system): Delete the code to initialize
coding->safe_charses
(intersection, find_safe_codings): New functions.
(Ffind_coding_systems_region_internal): New function.
(syms_of_coding): Defsubr it.  Initialize Qsafe_chars,
Qsafe_cding_system.  Make Vchar_coding_system_table a Lisp
variable and initialize it.