Update AutoloadGenerator.php

This should fix an issue with this commit:
https://github.com/composer/composer/commit/87a42c2f01936e6fd8973fac159dc8117114bebc

This commit is causing a parse error in autoload_namespaces.php:
return array(
    'zsql' => 'phar://' . '$vendorDir . '/jbboehr/zsql/build/zsql.phar',

A similar problem happens when using autoload.files as well.

This is what I'm using in composer.json, for reference:

  "autoload": {
    "psr-0": {
      "zsql": "build/zsql.phar"
    }
  },