[ClassLoader] fixed PHP warning on PHP 5.3

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Indeed. +1 for 0. Now you make me wonder why you choose 1001 :)