fix for `vector-{ref,set!}' on chaperone/impersonator on some platforms  --- fixes a81917a2692; drop this commit if that one is dropped
fix for `vector-{ref,set!}' on chaperone/impersonator on some platforms
 --- fixes a81917a2692; drop this commit if that one is dropped

mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket