-thread & -pthread are still treated as libraries, will need
additional work to use them as CFLAGS.
Eliminated HAVE_DCE define (was redundant) and its use. Code
now relies on draft4 and function existance tests.
SHA1 support is contributed by Daniel J. Gregor <dj@gregor.com>
MD5 support is contributed by me <kurt@OpenLDAP.org>
Uses public domain MD5 routines
Uses ISC/IBM freely redistributable Base64 routines
SHA1 support requires external SHA1 routines