Downgrade the dns_clientinfo_t structure to not contain dbversion

The DNS_CLIENTINFOMETHODS_VERSION and _AGE was bumped to 2 and 1 respectively, but the clientinfomethods->dbversion() method is not used anywhere and instead clientinfo->dbversion() method is the correct way of accessing the method.

There's also now way how to set the function, so it is always NULL.

We should also probably have a test that dlz_minimal.h versions are always equal or lower than the clientinfo.h versions, but that could be solved in a separate ticket.

Closes #971 (closed)

Merge request reports