To reproduce:
1) ./configure --with-apxs=/usr/local/apache1317/bin/apxs
--with-mysql=/usr/local/mysql --enable-debug=no
--enable-track-vars=yes --with-gdbm --enable-ftp --with-xml
--with-curl --with-openssl --with-pfpro --with-zlib=/usr/lib

NOTE 1: I have placed the path to the pfpro lib and it did not make a difference.

NOTE 2: I have also configured it with only pfpro to verify that it was not any other modules and it did not make a difference.

2) make
This is the result
root@server5:/usr/local/phpApache/php-4.0.4pl1# make > make.out
pfpro.c: In function `php_if_pfpro_version':
pfpro.c:129: warning: initialization makes pointer from integer without a
cast
root@server5:/usr/local/phpApache/php-4.0.4pl1#

NOTE: I sent the output into make.out so I could just see the errors.

3) make install
4) cd to apache install dir and run configtest.  It will give the following result:
root@server5:/usr/local/phpApache/php-4.0.4pl1# ../../apache/bin/apachectl
conf
igtest
Syntax error on line 213 of /usr/local/apache1317/conf/httpd.conf:
Cannot load /usr/local/apache1317/libexec/libphp4.so into server:
/usr/local/apache1317/libexec/libphp4.so: undefined symbol: PNVersion
root@server5:/usr/local/phpApache/php-4.0.4pl1#

I believe the error is in the ext/pfpro.c code (../php-4.0.4pl1/ext/pfpro/pfpro.c)----
/* {{{ proto string pfpro_version()
   Returns the version of the Payflow Pro library */
PHP_FUNCTION(pfpro_version)
{
        if (ZEND_NUM_ARGS() != 0) {
                WRONG_PARAM_COUNT;
        }

        RETURN_STRING(PNVersion(), 1);
}

I have gone in and commented out all the lines in pfpro.c and php_pfpro.h that referenced the pfpro version function.  Doing this and repeating the above steps allowed me to get apache up and running but it would seg fault at times so this is not a very good solution.  I have not submitted a gdb because I can't get it start without my commented changes.  Additionally, if I don't build it wil pfpro it configs, makes, and runs fine.