Cmake for Bro

I noticed that ClamAV support is always disabled because Bro has yet to migrate to a newer API. How should this be handled for the CMake port?

I already implemented it as an always disabled and unadvertised feature, but maybe that was too much?

- Jon

They removed the support for virus scanning buffers instead of files and when I checked a few days ago, that API was still gone. I'd say the clamav support is officially dead at this point.

  .Seth

Ack. Thanks for checking, let's remove it.

Robin