ports-mgmt/pkg_search: Remove deprecation, but IGNORE on DragonFly

At the request of a user, further review reveal that the pkg_* tools
aren't actually used. It just awks the INDEX file. The maintainer
forgot the technical details, especially since the SEE ALSO section of
the man page references pkg_* tools.

A minor update is needed to re-support DragonFly and update the man
page. Until this, it's been marked IGNORE for DragonFly.