(load_charset_map): Fix previous change.

(load_charset_map): Fix previous change.
(read_hex): Don't treat SPC as a comment starter.
(decode_char): If CODE_POINT_TO_INDEX retruns -1, always return
-1.
(Fdecode_char): Fix typo.
(CODE_POINT_TO_INDEX): Utilize `code_space_mask'
member to check if CODE is valid or not.
(Fdefine_charset_internal): Initialize `code_space_mask' member.
(encode_char): Before calling CODE_POINT_TO_INDEX, check if CODE
is within the range of charset->min_code and carset->max_code.