This is overkill. Unfortunately, there is no clear solution at hand without changing the way the extension itself work. It is a symptom of a wider flawed design of Geshi. There should be no need for each language to have its own stylesheet.
Switch to [[ http://pygments.org/ | Pygments ]]:
* [x] Initial commit. https://gerrit.wikimedia.org/r/218584
* [x] Add back-compat aliases for Geshi language names.
* [x] Ship the Pygments library. https://gerrit.wikimedia.org/r/219512
* [ ] Add parser tests to prevent regressions in html output.
* [ ] Ensure Geshi.compat.php escapes text.