DTrace firing throws

I assume you know what you're doing, so you can consider this pull request more as an illustrated question. Currently, I can not see how the dtrace firing can actually work with dtrace-provider 0.2.4 on a platform that does not support dtrace.

Anyway, I'm using this project on linux with this patch applied and since it follows the syntax in dtrace-provider's readme I don't see a reason that it should break other platforms.

Maybe you actually want to prevent it from working on a non dtrace enabled platform?