use pthread_kill() instead of pthread_cancel() to terminate SD_msg_chan

use pthread_kill() instead of pthread_cancel() to terminate SD_msg_chan

- fix a dead lock after a protocol error
- bdir_get_msg() use locks, SQL, FILE*.
  This is not compatible with pthread_cancel()
  while (!job_canceled(jcr) && (n=bget_dirmsg(sd)) >= 0)
  The msg_thread uses bdir_get_msg()  to dispatch Jmsg,
  and do catalog information

- moved the code in new terminate_sd_msg_chan_thread(JCR)