provide prototype in lutil.h
use LBER_SOCKET_T instead of int in prototype.  (didn't use
	ber_socket_t so all of lber.h wouldn't have be dragged in)
rename signal handlers, use RETSIGTYPE, and make SIGHUP wake
rename fd to sd to reflect descriptor must be usable as a socket.
renamed sel_exit_fds to wake_sds to reflect current use
improve readability of sockpeer.c including removing obtuse goto.

not assume LDAP_SIGUSR2

socketpair.  Use dependent on useful detection is.

Use them in slapd/str2filter.c.

Caller is required to call ldap_charray_free as needed.

instead of WSAGetLastErrorString to preserve errno like semantics.

errno.

Use strerror() if available.

Use a UDP socket connected to itself to allow signals to terminate the
select() in slapd_daemon_task().