Include <limits.h> in UTF-2000.

Include <limits.h> in UTF-2000.
(BT_UINT8_MIN): New macro in UTF-2000.
(BT_UINT8_MAX): New macro in UTF-2000.
(BT_UINT8_t): New macro in UTF-2000.
(BT_UINT8_nil): New macro in UTF-2000.
(BT_UINT8_unbound): New macro in UTF-2000.
(INT_UINT8_P): New inline function in UTF-2000.
(UINT8_VALUE_P): New inline function in UTF-2000.
(UINT8_ENCODE): New inline function in UTF-2000.
(UINT8_DECODE): New inline function in UTF-2000.
(mark_uint8_byte_table): New function in UTF-2000.
(print_uint8_byte_table): New function in UTF-2000.
(uint8_byte_table_equal): New function in UTF-2000.
(uint8_byte_table_hash): New function in UTF-2000.
(make_uint8_byte_table): New function in UTF-2000.
(uint8_byte_table_same_value_p): New function in UTF-2000.
(BT_UINT16_MIN): New macro in UTF-2000.
(BT_UINT16_MAX): New macro in UTF-2000.
(BT_UINT16_t): New macro in UTF-2000.
(BT_UINT16_nil): New macro in UTF-2000.
(BT_UINT16_unbound): New macro in UTF-2000.
(INT_UINT16_P): New inline function in UTF-2000.
(UINT16_VALUE_P): New inline function in UTF-2000.
(UINT16_ENCODE): New inline function in UTF-2000.
(UINT16_DECODE): New inline function in UTF-2000.
(UINT8_TO_UINT16): New inline function in UTF-2000.
(mark_uint16_byte_table): New function in UTF-2000.
(print_uint16_byte_table): New function in UTF-2000.
(uint16_byte_table_equal): New function in UTF-2000.
(uint16_byte_table_hash): New function in UTF-2000.
(make_uint16_byte_table): New function in UTF-2000.
(uint16_byte_table_same_value_p): New function in UTF-2000.
(print_byte_table): New function in UTF-2000.
(byte-table): Use `print_byte_table' as printer.
(make_byte_table): Delete second argument `older'.
(byte_table_same_value_p): New function in UTF-2000.
(copy_byte_table): Deleted.
(get_byte_table): New function in UTF-2000.
(put_byte_table): New function in UTF-2000.
(print_char_id_table): New function in UTF-2000.
(char-id-table): Use `print_char_id_table' as printer.
(make_char_id_table): Delete second argument `older'.
(get_char_id_table): Use `get_byte_table [new implementation].
(put_char_id_table): Use `get_byte_table and `put_byte_table' [new
implementation].
(Ffind_char_attribute_table): New function in UTF-2000.
(mark_charset): Mark `cs->encoding_table' in UTF-2000.
(syms_of_mule_charset): Add LRECORD_IMPLEMENTATION `uint8_byte_table'
and `uint16_byte_table' in UTF-2000.
(syms_of_mule_charset): Add new function `find-char-attribute-table'
in UTF-2000.