Optimize copying-quicksort by passing around only two indexes and the length of the block.
Optimize copying-quicksort by passing around only two indexes and the
length of the block.

svn: r17005

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