Add new port dns/powerdns-recursor40

[krion]

Summary

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=224297

Upstream version 4.1.0 dns/powerdns-recursor40 doesn't build on
FreeBSD < 10.4, as there's no _cxa_thread_atexit() support in
FreeBSD libc, we've got multiple requests to support 4.0.x branch in
the future and on FreeBSD 10.3 as well.

[mat]

Please make sure this is done as a repocopy from rP455510.