Avoid call time pass by reference

PHP deprecated call time pass by reference, but the module does this:

function libraries_detect($libraries) {
  foreach ($libraries as $name => $library) {
    libraries_detect_library(&$libraries[$name]);
  }
  return $libraries;
}

function libraries_detect_library(&$library) {
 // ...
}

Basically it tries to avoid foreach copying the value and instead would like to get the original value to work with. We can do that much easier with PHP 5's foreach reference syntax, just need to move the &, so it becomes:

function libraries_detect($libraries) {
  foreach ($libraries as &$library) {
    libraries_detect_library($library);
  }
  return $libraries;
}

function libraries_detect_library(&$library) {
 // ...
}

The attached patch does this. Foreach is capable to do this in PHP 5 and Drupal 7 already requires PHP 5, so I did not bother putting the PHP requirement into the .info file.