games/shaaft: Deprecate port.

This has been abandoned upstream a decade plus ago (nearly two),
it resides in the attic of an attic (download only, not even a
web page), does not build with clang (10+ years) and requires
increasing contortions to build with GCC even. All that without
proper maintenance on the FreeBSD, either.

So deprecate with a generious expiration window (3 months).

PR: 281233