Editing screen for a particular language.
$langcode: Language code of the language to edit.
function language_admin_edit_form($form, &$form_state, $language) {
_language_admin_common_controls($form, $language);
$form['actions'] = array(
'#type' => 'actions',
);
$form['actions']['submit'] = array(
'#type' => 'submit',
'#value' => t('Save language'),
);
$form['#submit'][] = 'language_admin_edit_form_submit';
$form['#validate'][] = 'language_admin_edit_form_validate';
return $form;
}