kludge to make WordPress' Google Sitemap Generator exclude Page Links To pages linking to PDF files

gistfile1.phtml

<?php

function filterSitemapOptions($opts) {
    global $wpdb;

    // tell it to exclude any pages that are just page-links-to links to PDF files
    $exclude = $wpdb->get_col("select post_id from $wpdb->postmeta where meta_key = '_links_to' and meta_value like '%.pdf'");
    if (!empty($exclude)) {
        $opts['sm_b_exclude'] = array_merge($opts['sm_b_exclude'], $exclude);
    }

    return $opts;
}

add_filter('option_sm_options', 'filterSitemapOptions');