Complain properly about unterminated comments in config files.

Complain properly about unterminated comments in config files.

sylar noticed that unterminated comments would often cause an
infinite loop in the config parser.

src/recdb.c (fail_codes): Add UNTERMINATED_COMMENT value.
  (parse_skip_ws): Abort with that on EOF inside a comment.
  (failure_reason): Handle UNTERMINATED_COMMENT.