Add chroot back to BIND's startup script.

[mat]

Summary

• Add a mtree file to setup the chroot cage.
• Rename internal variables in the rc file with an _ prefix.
• Move rc variables description at the top.
• Always use ${} for variables in the rc file.

[mat]

Debug some stuff, copy OpenSSL engines to the chroot if they are present. (even
if they're not needed.)

[mat]

Add BIND9 9.10.

[dim]

Just FYI, this makes port installation fail with:

===>  Installing for bind910-9.10.2
===>  Checking if bind910 already installed
===>   Registering installation for bind910-9.10.2
pkg-static: Unable to access file /usr/work/share/dim/ports/dns/bind910/work/stage/usr/local/etc/namedb/named.conf.sample: No such file or directory
pkg-static: Unable to access file /usr/work/share/dim/ports/dns/bind910/work/stage/usr/local/etc/namedb/named.root: No such file or directory
pkg-static: Unable to access file /usr/work/share/dim/ports/dns/bind910/work/stage/usr/local/etc/namedb/master/empty.db: No such file or directory
pkg-static: Unable to access file /usr/work/share/dim/ports/dns/bind910/work/stage/usr/local/etc/namedb/master/localhost-forward.db: No such file or directory
pkg-static: Unable to access file /usr/work/share/dim/ports/dns/bind910/work/stage/usr/local/etc/namedb/master/localhost-reverse.db: No such file or directory
pkg-static: lstat(/usr/work/share/dim/ports/dns/bind910/work/stage/usr/local/etc/namedb/dynamic/): No such file or directory
pkg-static: lstat(/usr/work/share/dim/ports/dns/bind910/work/stage/usr/local/etc/namedb/master/): No such file or directory
pkg-static: lstat(/usr/work/share/dim/ports/dns/bind910/work/stage/usr/local/etc/namedb/slave/): No such file or directory
pkg-static: lstat(/usr/work/share/dim/ports/dns/bind910/work/stage/usr/local/etc/namedb/working/): No such file or directory
*** [fake-pkg] Error code 74

[mat]

In D1952#13, @dim wrote:

Just FYI, this makes port installation fail with:

===>  Installing for bind910-9.10.2
===>  Checking if bind910 already installed
===>   Registering installation for bind910-9.10.2
pkg-static: Unable to access file /usr/work/share/dim/ports/dns/bind910/work/stage/usr/local/etc/namedb/named.conf.sample: No such file or directory
pkg-static: Unable to access file /usr/work/share/dim/ports/dns/bind910/work/stage/usr/local/etc/namedb/named.root: No such file or directory
pkg-static: Unable to access file /usr/work/share/dim/ports/dns/bind910/work/stage/usr/local/etc/namedb/master/empty.db: No such file or directory
pkg-static: Unable to access file /usr/work/share/dim/ports/dns/bind910/work/stage/usr/local/etc/namedb/master/localhost-forward.db: No such file or directory
pkg-static: Unable to access file /usr/work/share/dim/ports/dns/bind910/work/stage/usr/local/etc/namedb/master/localhost-reverse.db: No such file or directory
pkg-static: lstat(/usr/work/share/dim/ports/dns/bind910/work/stage/usr/local/etc/namedb/dynamic/): No such file or directory
pkg-static: lstat(/usr/work/share/dim/ports/dns/bind910/work/stage/usr/local/etc/namedb/master/): No such file or directory
pkg-static: lstat(/usr/work/share/dim/ports/dns/bind910/work/stage/usr/local/etc/namedb/slave/): No such file or directory
pkg-static: lstat(/usr/work/share/dim/ports/dns/bind910/work/stage/usr/local/etc/namedb/working/): No such file or directory
*** [fake-pkg] Error code 74

this has been committed, please open a PR.

[dim]

Sorry, false alarm. I had some customizations in the Makefile that I totally forgot about. Reverting those made the port build and install correctly.