Function always reference itself

Issue Summary

The parser fails to remove the hit to the function definition while grep-ing through the function body.
As a result, the function always shows up in the "Functions that call xx" list, even if there is no recursive calls (for example: http://api.drupal.org/api/function/system_perm/6/references).

Some code was there to prevent that, but it's currently broken.

Here is a patch that fixes the issue.