Plus more pthread rwlock code

Update configure and depend --enable-dnssrv upon finding res_query
Update back-dnssrv to better handle ManageDSAit control

  configure.in: check for AIX security library, set in AUTH_LIBS macro
  top.mk: add AUTH_LIBS macro to SECURITY_LIBS
  portable.h.in: added HAVE_AIX_SECURITY macro (via autoheader)
  passwd.c: use AIX getuserpw in chk_unix. Also fix logic in chk_unix:
  	getpwnam must always succeed for the given user. It is not a
	fatal error if getspnam returns no result for the user: On
	systems that support /etc/shadow, its usage is optional. The
	same logic applies for AIX, SCO/HP SecureWare, etc.

ol_link_sasl vs ol_link_spasswd is confusing.

Fix --disable-spasswd

against Cyrus SASLdb.  Like other cleartext mechanisms,
should be protected from eavesdropping.

2 more steps left: add back-sql directory itself, and update Win32 build environment.

plus these changes unhidden changes:
	remove now meaning --enable-discreteaci configure option
	fix ITS#451, slapd filters
	Add ber_bvecadd() to support above
	constify ldap_pvt_find_wildcard() and misc slapd routines
	renamed some slap.h macros
	likely broken something

one can select NDBM as NDBM is not supported.

under "auto" selection.  If not auto, just warn.
Rebuild configure using appropriate tools.

simple bind via:
	{KERBEROS}principal
Code is disabled by default (for security reasons).  Use
--enable-kpasswd to enable.  Behind SLAPD_KPASSWD.
Reworked Kerberos detection and split out KBIND as independent
feature (--disable-kbind) (LDAP_API_FEATURE_X_OPENLDAP_V2_KBIND).
KBIND depends upon detection of KRB4 (or KRB425) support.  Detection,
building with eBones (as distributed with FreeBSD 3.4) okay, but
wasn't able to test as I don't have a K4 KDC handy.
--with-kerberos has a number of detection options... most likely
don't work properly.

support for DCE slash-delimited, left-to-right DNs;
support for a domain socket transport (enable with
--enable-ldapi); and extensions to URL parsing to
support the latter transport.

manual push bytes about.  Allows ber_*_t to be any 32-bit or
larger type.  Reworked AC_{HTON,NTOH}{L,S} macros to care only
about 32-bit (netlong) and 16-bit (netshort) reordering as
needed for BSD socket interface.

Select appropriopriate hton{s,l} function to use in lber-int.h.

an integer type of exactly 32 bits.