[9.18] fix: usr: Don't allow statistics-channel if libxml2 and libjson-c are unsupported
When the libxml2 and libjson-c libraries are not supported, the statistics channel can't return anything useful, so it is now disabled. Use of statistics-channel
in named.conf
is a fatal error.
Closes #4895 (closed)
Backport of MR !9423 (merged)