Attached a simple debdiff that will enable the requested json support. This also disables json support in the udeb build, which avoids https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=833307 and is already done for the xml stats too.
To test, install bind and add this to /etc/bind/named.conf.local:
statistics-channels {
inet * port 8888
allow { 127.0.0.1; };
};
After restarting bind9, try "wget http://localhost:8888/json" to get json
stats. The xml endpoint continues to work too: http://localhost:8888/xml
856905.debdiff
Description: Binary data

