sc-im marked broken on aarch64

[Mark Linimon]

I've committed the fix.  Thanks for reporting and testing.

fwiw, my goal in marking ports BROKEN on the various tier-2 archs is to
bring more attention to them.  We still have a lot of work to do on the
arm archs in particular to bring things up to parity with amd64 (well,
as much as we can, in any case.)  All help is welcome!

For more, please see:

  https://wiki.freebsd.org/arm64/ports
  https://wiki.freebsd.org/armv6/ports

Thanks.

mcl