Don't include example.zone test data file in dist tarball.
It is generated from an .in file via ./configure.
This was noticed by emhn during Debian packaging.
(distclean created a source different than extract tarball.)
I didn't get okay, but I mentioned my patch on jabber.
I tested on one system. This seems to be trivial.
EXTRA_DIST += spec.spec
EXTRA_DIST += example.com
-EXTRA_DIST += example.zone
EXTRA_DIST += example.sqlite3
EXTRA_DIST += example-base-inc.zone example-nsec3-inc.zone