pict: restore use of loaded mask, if any, by `bitmap`
pict: restore use of loaded mask, if any, by `bitmap`

In case a `bitmap%` object with a mask is passed to `bitmap`.

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