Milter-greylist

Hi,

I want to be able to do this:

http://milter-greylist.wikidot.com/geoip

I'm using EL5 (a Red Hat 5 derivative) and when I try to compile (from spec)
it comes back with:

checking for pthread_create in -lpthread... no
checking for pthread_create in -lc_r... no
checking for pthread_create in -lpthreads -lpthread... no
Required libpthread not found. Use --with-libpthread
error: Bad exit status from /var/tmp/rpm-tmp.55653 (%build)

Any ideas what packages I need to install to make milter-greylist compile with
GeoIP support?

Thanks.

Michael.