observation to be noted in cache. Fix bug where EDNSprobe halted
exponential backoff if EDNS status unknown.
- new unresponsive host method, exponentially increasing block backoff.
- iana portlist updated.
git-svn-id: file:///svn/unbound/trunk@2303 be551aaa-1e26-0410-a405-d3ace91eadb9