[CentOS] Problem building latest Courier-authlib on CentOS4

Upgrading to CentOS6 is on my list, but I'm trying to get the latest Courier-MTA running at the moment.

I downloaded the current courier tarballs and tried to build the rpms on a CentOS4 system.  I got these errors:

$ rpmbuild -tb courier-authlib-0.64.0.tar.bz2
...
libtool: link: ar cru .libs/libauthpipe.a  authpipe.o authpipelib.o
libtool: link: ranlib .libs/libauthpipe.a
libtool: link: ( cd ".libs" && rm -f "libauthpipe.la" && ln -s
"../libauthpipe.la" "libauthpipe.la" )
libtool: link: gcc -I/usr/include/mysql -g -pipe -m32 -march=i386
-mtune=pentium4 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
-fno-strict-aliasing -I/usr/include -O2 -g -pipe -m32 -march=i386
-mtune=pentium4 -Wall -I.. -I./.. -o authdaemontest authdaemontest.o 
./.libs/libcourierauthcommon.a
/home/bowieb/rpm/BUILD/courier-authlib-0.64.0/.libs/libcourierauth.a -ldl
libtool: link: cannot find the library `libltdl/libltdlc.la' or
unhandled argument `libltdl/libltdlc.la'
make[2]: *** [authdaemondprog] Error 1
make[2]: *** Waiting for unfinished jobs....
libtool: link: gcc -I/usr/include/mysql -g -pipe -m32 -march=i386
-mtune=pentium4 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
-fno-strict-aliasing -I/usr/include -O2 -g -pipe -m32 -march=i386
-mtune=pentium4 -Wall -I.. -I./.. -o .libs/authpasswd authpasswd.o 
./.libs/libcourierauthcommon.so
/home/bowieb/rpm/BUILD/courier-authlib-0.64.0/.libs/libcourierauth.so
libhmac/.libs/libhmac.a md5/.libs/libmd5.a sha1/.libs/libsha1.a
rfc822/.libs/libencode.a -ldl -Wl,-rpath -Wl,/usr/lib/courier-authlib
make[1]: *** [all-recursive] Error 1
make: *** [all] Error 2
error: Bad exit status from /var/tmp/rpm-tmp.93944 (%build)


RPM build errors:
    Bad exit status from /var/tmp/rpm-tmp.93944 (%build)

I asked on the Courier list and Sam said that my libtool is too old.  He suggested adding an "autoreconf" line to the spec file, but that just generated an error that my Autoconf is too old.

Can someone give me a pointer as to how to fix this?

Thanks

-- 
Bowie