A problem with libpq

Can anyone help me with this problem?

I have installed postgresql-7.2.1 and am trying to compile one of the
test programs from the directory src/test/examples.

I have compiled the example successfully on my Red Hat Linux machine and
now need to compile it on my SCO machine but keep getting errors that
seem to mean that I have forgotten to use the "-lpq" option when
compiling. I am running an old version of SCO Openserver 5

I am using the following command:

cc testlibpq.c -I/usr/local/pgsql/include -L/usr/local/pgsql/lib -lpq
-otestlibpq

I receive the following error messages:

undefined first referenced
symbol in file
PQfinish testlibpq.o
PQsetdbLogin testlibpq.o
PQstatus testlibpq.o
PQerrorMessage testlibpq.o
PQexec testlibpq.o
PQresultStatus testlibpq.o
PQclear testlibpq.o
PQnfields testlibpq.o
PQfname testlibpq.o
PQgetvalue testlibpq.o
PQntuples testlibpq.o
ld fatal: Symbol referencing errors. No output written to testlibpq

As far as I can see (and I am unfamiliar with libraries, etc)
/usr/local/pgsql/lib seems okay. It has the following files in it:

-rw-r--r-- 1 root sys 79756 Jul 30 2002 libpq.a
-rwxr-xr-x 1 root sys 67600 Jul 30 2002 libpq.so@
-rwxr-xr-x 1 root sys 67600 Jul 30 2002 libpq.so.2@
-rwxr-xr-x 1 root sys 67600 Jul 30 2002 libpq.so.2.2

In my ignorance, I take it that libpq.so.2.2 is the real file and that
libpq.so is simply a link to it.