PLPerl - Undefined symbol "MemoryContextSwitchTo"

Due to database corruption, I had to rebuild a database. Originally we
installed PGSQL 7.4 and over the years bumped it up to 8.0. Now I would like
to use 8.4.

I'm trying to apply the plperl language to a 8.4.0_1 SQL_ASCII database and
I keep getting this error message:

orion-root@/home/postgres: createlang plperl erp
createlang: language installation failed: ERROR: could not load library
"/usr/local/lib/postgresql/plperl.so": dlopen
(/usr/local/lib/postgresql/plperl.so) failed:
/usr/local/lib/postgresql/plperl.so: Undefined symbol
"MemoryContextSwitchTo"

I checked to see if p5-postgresql-plperl was installed and it wasn't.

orion-root@/usr/ports: portversion -v | grep p5-postgresql-plperl
orion-root@/usr/ports:

I noticed this:

orion-root@/usr/ports: make search name=postgresql-plperl
Port: postgresql-plperl-7.4.25_1
Path: /usr/ports/databases/p5-postgresql-plperl
Info: Write SQL functions for PostgreSQL using Perl5
Maint: girgen(at)FreeBSD(dot)org
B-deps: gettext-0.17_1 gmake-3.81_3 libiconv-1.13.1 perl-5.8.9_3
R-deps: gettext-0.17_1 libiconv-1.13.1 perl-5.8.9_3 postgresql-client-7.4.25
postgresql-server-7.4.25
WWW: http://www.postgresql.org/

I find this surprising that the plperl module depends on an older version of
PGSQL! Perl 5.8.9 is also depended on. I'm running Perl 5.10.1.

orion-root@/home/postgres: uname -a
FreeBSD orion.dawnsign.com 7.1-RELEASE-p3 FreeBSD 7.1-RELEASE-p3 #3: Fri Feb
27 14:11:28 PST 2009
root(at)orion(dot)dawnsign(dot)com:/usr/obj/usr/src/sys/ORION-SMP i386

Does this mean I have to revert back to the older version of PGSQL as well
as an older version of Perl in order to install plperl language support?

~Doug