4421. [func] When built with LMDB (Lightning Memory-mapped
Database), named will now use a database to store
the configuration for zones added by "rndc addzone"
instead of using a flat NZF file. This improves
performance of "rndc delzone" and "rndc modzone"
significantly. Existing NZF files will
automatically by converted to NZD databases.
To view the contents of an NZD or to roll back to
NZF format, use "named-nzd2nzf". To disable
this feature, use "configure --without-lmdb".
[RT #39837]
