Update lang/racket and lang/racket-minimal to version 6.5.
- Use prebuilt Racket packages to prevent building during the
staging phase (PR 200101).
Prevent inclusion of libunique, which brings in GTK2, which
then conflicts with the default GTK3 toolkit.
Include commit f16f54a from github/racket/racket, which fixes
semaphore handling when futures are disabled (this broke the
IDE).(Only the first 15 lines of the commit message are shown above )