* all others: Added DESTDIR support

when not needed.

  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.

also description of .pid and .args files.

  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.

Add basics of Kerberos detection.