building with -m64

["Kurt D. Zeilenga" <Kurt@OpenLDAP.org>]

So, I had to build OpenLDAP on a PPC64 system today.
Not too bad.  Aside from CFLAGS=-m64, I had to hack
libtool to pass -m64 with -shared when building
shared libraries and hack libtool to look in
{,/usr}/lib64 instead of {,/usr}/lib for .la files.

Now I have to consider whether it best to hack our
version of libtool (which should be relatively
easy) or attempt to upgrade to the latest libtool
(which I know will be a real chore, given autoconf
files will also need to be upgraded).

Kurt