Description:
------------
The "The use statement with non-compound name '%s' has no effect" warning is only thrown when the use statement doesn't have a leading backslash. It should be thrown in both cases as they are semantically equivalent.

(Patch is trivial: Get rid of the is_global arg altogether.)

Test script:
---------------
<?php
namespace {
    use Exception;
}
namespace {
    use \Exception;
}

// http://codepad.viper-7.com/vN34cx

Expected result:
----------------
Two warnings.

Actual result:
--------------
One warning.