Before I go on and do Linux (unless someone else volunteers :P),
I'd like to get some feedback on this patch. It works on Mac now too.
I still didn't add the functions to get proper names or unique ids for
joysticks. What I'm mainly interested in is your thoughts on using
intptr_t ids instead of ALLEGRO_JOYSTICK * pointers. The ids
actually are ALLEGRO_JOYSTICK * pointers, but the user doesn't
have to know that. The external API uses intptr_t while internally
it just casts to ALLEGRO_JOYSTICK * so I didn't have to do _too_
much work.