title: posts_where set only one custom post type using hook
body: <p>in my wordpress pulgin i used the <code>post_where</code> filter but it's effect all other post type of my site.</p>
  
  <p>my question is how to set this filter only for <code>"property"</code> post only</p>
  
  <pre><code>add_filter('posts_where', 'posts_where'); 
  
  function posts_where($where)
  {
         global $wpdb,$wp_query;
         $where .= ' AND latitude.meta_key="wp_gp_latitude" ';
         $where .= ' AND longitude.meta_key="wp_gp_longitude" ';  
  
      return $where;
  } 
  </code></pre>