Fix "making delay-mode-hooks buffer-local" message

On evaluation I am always getting 
```
Making delay-mode-hooks buffer-local while locally let-bound!
```

Fix this by avoiding let; `delay-mode-hooks` need not be let-bound because it's a permanent local variable.

I'll eventually remove `clojure-font-lock-setup` as it's not idiomatic to have such a function exposed. I haven't found a better way to "borrow" font-locking from a major mode that's universal. I've played with the idea used [here](https://github.com/nex3/haml-mode/blob/master/haml-mode.el#L120), but didn't manage to get it working for clojure-mode and java-mode. Feel free to implement an alternative solution.