MDL-58670 blog: respect capability to search entries

blog/lib.php

@@ -873,7 +873,7 @@ function blog_get_headers($courseid=null, $groupid=null, $userid=null, $tagid=nu
         }
 
         // Append Search info.
-        if (!empty($search)) {
+        if (!empty($search) && has_capability('moodle/blog:search', $sitecontext)) {
             $headers['filters']['search'] = $search;
             $blogurl->param('search', $search);
             $PAGE->navbar->add(get_string('searchterm', 'blog', $search), $blogurl->out());