Make it honor attrs and attrsonly

problem reported in IT78. Index files will still be stale if the modrdn
uses deleteoldrdn.

The Root DSE does not depend on SLAPD_CONFIG_DN and friends.
Added a comment for supportedSASLMechanism to root_dse.c

Beginning of ROOT DSE support

Move declaration of st

Add test listener no-thread_create experiment (behind ifdef).

I moved slap_shutdown after the waitforkids.  I also wait for each process to complete before returning from fork_child since I had two lockups on my NT box.

Cleanup perl detection.