Signup Cancel hook needs a uid parameter

The user id of the user to cancel the signup for needs to be passed to the various functions for this to be properly useful.

function signup_cancel_signup($uid, $nid, $anon_mail = NULL) {
  //delete the selected user from the log table and return to the previous page
  if ($anon_mail) {
    db_query("DELETE FROM {signup_log} WHERE anon_mail = '%s'", $anon_mail);
  } else {
    db_query('DELETE FROM {signup_log} WHERE uid = %d AND nid = %d', $uid, $nid);
  }
  $node = node_load($nid);
  foreach (module_implements('signup_cancel') as $module) {
    $function = $module .'_signup_cancel';
    $function($node);
  }
  drupal_set_message(t('Signup to %title cancelled.', array('%title' => l($node->title, "node/$node->nid"))));
}