MFH: r393161 r395660 r395703 r395908

Update BIND to 9.9.7-P3 and 9.10.2-P4.

Also:

• Add an option to enable the bind min override ttl patch.
• When not using OpenSSL from ports, do not try to unmount the chrooted engines directory.
• Add an option for embedding PORTREVISION in the server's version string.

Security: CVE-2015-5722, CVE-2015-5986
Sponsored by: Absolight