* all others: Added DESTDIR support

	ldap_defaults.h incorporates non-generated ldapconfig.h values.
	ldap_config.h.in is new template for autoconf generated defaults
		(namely directories and paths)
	ldap_config.h.nt, NT template (must be manually copied)
	s/<ldapconfig.h>/<ldap_defaults.h>/
	s/DIRSEP/LDAP_DIRSEP/ & s/DEFAULT_/LDAP_/

Fix install of ldap_schema.h to use $(srcdir)

Install ldap_schema.h

  make depend, make tests, and make install all work when build directory
  is not the $srcdir.
Also modified library handling such that -lpthread more likely to be last.
WARNING: new orderring requires use of LDFLAGS to set global loader options
  such as -L/usr/local/lib.  If you put this in LIBS, some libraries
  may not be found a link time.
Likely broke Kerberos/LDAPD support.  Don't have those in my testbed.

  default sysconfdir subdirectory is openldap instead of ldap.
    This removes conflicts with other ldap subsystems.  Should
    be configure option.
  *.conf files are now preserved.  A *.conf.default are always
    created with the latest conf.
  *.help and ldapfriendly are now placed in $(datadir)/$(ldap_subdir)
  updated man pages to reflect changes.

  Updated to use libtool 1.2 (with FreeBSD3.0 a.out v. elf detection).
  Updated autoconf to 1.12 with sed patch (don't use stock 1.12).
  aclocal.m4 is built using automake's aclocal, v1.3.
  Updated mkdep to support libtool .lo files.
Updated automake provided macros for TERMIOS, STRTOD, MKTIME, PTRDIFF_T
Autoconf now checks to ensure C compiler supports ANSI C prototypes.
Updated make files templates.

  configure generates ldap_features.h based from ldap_features.h.in
  LDAP_REFERRALS -> LDAP_API_FEATURE_OPENLDAP_V2_REFERRALS
  LDAP_DNS -> LDAP_API_FEATURE_OPENLDAP_V2_DNS

Fix make install problems.

Now to sort out configure enable/with options.

handle ldapconfig.h.in.