MDL-58080 mod_scorm: add immutable header for scorm content files.

mod/scorm/lib.php

@@ -972,7 +972,7 @@ function scorm_pluginfile($course, $cm, $context, $filearea, $args, $forcedownlo
         $revision = (int)array_shift($args); // Prevents caching problems - ignored here.
         $relativepath = implode('/', $args);
         $fullpath = "/$context->id/mod_scorm/content/0/$relativepath";
-        // TODO: add any other access restrictions here if needed!
+        $options['immutable'] = true; // Add immutable option, $relativepath changes on file update.
 
     } else if ($filearea === 'package') {
         // Check if the global setting for disabling package downloads is enabled.