Remove infinite loop on ISC_R_NOFILE
When parsing a zonefile named-checkzone (and others) could loop infinitely if a directory was $INCLUDED. Record the error and treat as EOF when looking for multiple errors.
This was found by Eric Sesterhenn from X41.
Replaces https://gitlab.isc.org/isc-private/bind9/-/merge_requests/636
Closes #4357 (closed)