MDL-60105 mod_folder: Set timemodified on change

Changes to the folder contents were not resulting in the
timemodied of the folder activity being set. This prevented
global search from picking up the changes.

mod/folder/edit.php

@@ -61,11 +61,11 @@ if ($mform->is_cancelled()) {
 
 } else if ($formdata = $mform->get_data()) {
     $formdata = file_postupdate_standard_filemanager($formdata, 'files', $options, $context, 'mod_folder', 'content', 0);
-    $DB->set_field('folder', 'revision', $folder->revision+1, array('id'=>$folder->id));
-
-    // Update the variable of the folder revision so we can pass it as an accurate snapshot later.
+    $folder->timemodified = time();
     $folder->revision = $folder->revision + 1;
 
+    $DB->update_record('folder', $folder);
+
     $params = array(
         'context' => $context,
         'objectid' => $folder->id