More fixes for NT support:

  liblutil/ntservice.c change registry key path used for non-default
  	service names.
  slapd/Makefile.in change to generate slapd.syms dynamically
  slapd/daemon.c fix to make NT service ignore SIGBREAK
  slapd/main.c fix to allow NT to retrieve listening url from registry
  slapd/nt_svc.c fix for exported symbols
  slapd/result.c change use of strerror to sock_errstr
  slapd/slapd.syms no longer needed