BUG/MINOR: DNS request retry counter used for retry only

There are two types of retries when performing a DNS resolution:
1. retry because of a timeout
2. retry of the full sequence of requests (query types failover)

Before this patch, the 'resolution->try' counter was incremented
after each send of a DNS request, which does not cover the 2 cases
above.
This patch fix this behavior.
3 files changed