[racket] FFI dynamic library reloading

I've been doing writing some glue code between Cocoa and Racket and
part of that exists as a C library that I am communicating with via
FFI, and part of it is Racket code that uses the Objective C FFI
interface.

One thing I've noticed is that if I change the C library, I need to
restart DrRacket for it to be able to reload the changed dynamic
library.  It seems appears that the first time I run in DrRacket it
loads the library, but subsequent runs can only refer the library as
it existed on the first run.  I don't know if this is a limitation of
the platform or it is something specific to the way DrRacket loads
libraries.

It's lead me to use DrRacket as the editor and run my code via
gracket, but it would be nicer if I could still run it through
DrRacket as I make changes to the C library.

-- 
Christopher W. Bowron <chris at bowron.us>
[ Nothing is exciting if you know what the outcome will be ]
    - Joseph Campbell