MDL-56576 admin: Cannot edit blocks on search page

Admin search page was processing the blocks delete request before the blocks
could process it.

Added a hidden field to the search results form so it can be sure the form submission
was for saving admin settings.

admin/search.php

@@ -19,7 +19,7 @@ $errormsg  = '';
 $focus = '';
 
 // now we'll deal with the case that the admin has submitted the form with changed settings
-if ($data = data_submitted() and confirm_sesskey()) {
+if ($data = data_submitted() and confirm_sesskey() and isset($data->action) and $data->action == 'save-settings') {
     require_capability('moodle/site:config', $context);
     if (admin_write_settings($data)) {
         redirect($PAGE->url, get_string('changessaved'), null, \core\output\notification::NOTIFY_SUCCESS);

admin/templates/settings_search_results.mustache

@@ -37,6 +37,7 @@
 <form action="{{actionurl}}" method="post" id="adminsettings">
     <div>
         <input type="hidden" name="sesskey" value="{{sesskey}}">
+        <input type="hidden" name="action" value="save-settings">
     </div>
     <fieldset>
         <div class="clearer"></div>