- DF bit was on for COOKIE-ECHO chunks. This is

- DF bit was on for COOKIE-ECHO chunks. This is
  incorrect and should be OFF letting IP fragment
  large cookie-echos.
- Rename sysctl variable logging to log_level.
- Fix description of sysctl variable stats.
- Add sysctl variable log to make sctp_log readable via sysctl
  mechanism (this is by compile switch and targets non KTR platforms or
  when someone wants to do performance wise tracing).
 - Removed debug code

Approved by:	re@freebsd.org (B Mah)