Fix unserialize dictionary generation

We now have namespaced classes in here, and need to escape the
backslashes.

sapi/fuzzer/generate_unserialize_dict.php

@@ -3,7 +3,7 @@
 $dict = "";
 foreach (get_declared_classes() as $class) {
     $len = strlen($class);
-    $dict .= "\"$len:\\\"$class\\\"\"\n";
+    $dict .= "\"$len:\\\"" . addslashes($class) . "\\\"\"\n";
 }
 
 file_put_contents(__DIR__ . "/dict/unserialize", $dict);