filesystems/encfs: undeprecate and adopt

While this port is unmaintained up stream, it is useful to people
accessing directories encrypted with encfs. The recommended
alternative, gocryptfs, currently does not build on FreeBSD due to
missing platform-specific bits. Keep the port around at least until
gocryptfs has FreeBSD support.

PR: 282351
Approved by: dmgk (maintainer timeout)