hs_err improvement: handle class path longer than O_BUFLEN

If the length of the class path is longer than O_BUFLEN, a warning such as the following would result and the class path would be truncated in the hs err log.

Java HotSpot(TM) 64-Bit Server VM warning: outputStream::do_vsnprintf output truncated -- buffer length is 2000 bytes but 3164 bytes are needed.