`set-argb-pixels' needs to pre-multiply alpha for a alpha-channel bitmap  Closes PR 11571
`set-argb-pixels' needs to pre-multiply alpha for a alpha-channel bitmap
 Closes PR 11571

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