Update lang/racket and lang/racket-minimal to version 6.5.

• Use prebuilt Racket packages to prevent building during the staging phase (PR 200101).

• patch-share_pkgs_gui-lib_mred_private_wx_gtk_queue.rkt
  
  Prevent inclusion of libunique, which brings in GTK2, which then conflicts with the default GTK3 toolkit.

• patch-src_racket_src_future.c
  
  Include commit f16f54a from github/racket/racket, which fixes semaphore handling when futures are disabled (this broke the IDE).

• Add options for FUTURES and JIT (i386/amd64 only).

• Remove unnecessary patches.

~ Credits ~

Juan Francisco Cantero Hurtado (OpenBSD maintainer) - kindly
brought me up to speed on Racket's status and prebuilt packages,
so I could remove lots of cruft from the port.

Sam Tobin-Hochstadt - tracked down the futures issue.

PR: 200101
Differential Revision: https://reviews.freebsd.org/D6984
Differential Revision: https://reviews.freebsd.org/D6985
Reviewed by: Martin Sugioarto