raco pkg: preserve/adjust timestamps when extracting/creating packages
raco pkg: preserve/adjust timestamps when extracting/creating packages

Perserve and adjust timestamps in a way that helps make re-packing an
installed-from-built package produce an archive with the same checksum
as the original.

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