[racket] disable inlining for recursive functions

At Fri, 7 Dec 2012 07:38:11 -0600,
Robby Findler wrote:
> 
> It does sound like a pretty painful process, tho, to manually inline
> things. Also abstraction breaking.

Macros make it a lot less painful. In a lot of cases, `define-syntax-rule'
is all you need.

Sam wrote a `define-inline' macro that makes manual inlining even easier.
I'm currently making it more robust, and will make it available once
that's done.

Vincent