Disable update service editing by default for multisite. See #12229.

Introduce __return_false for simple filtering. See #12381.

git-svn-id: https://develop.svn.wordpress.org/trunk@13413 602fd350-edb4-49c9-b593-d223f7449a82

wp-includes/functions.php

@@ -4042,4 +4042,15 @@ function get_file_data( $file, $default_headers, $context = '' ) {
 function _search_terms_tidy($t) {
 	return trim($t, "\"'\n\r ");
 }
+
+/**
+ * Returns false
+ *
+ * Useful for returning false to filters easily
+ * 
+ * @return bool false
+ */
+function __return_false() {
+	return false;
+}
 ?>