daemon/tls: fix a double-free for some cases of policy.TLS_FORWARD

The double-free may have happened in some cases when the upstream resolver was stopped while answering a forwarded query. I was reliably reproducing it by running resperf on two kresd instances with one forwarded to the other, and killing the upstream one.

added bug label

requested review from @vcunat

added 6 commits

• 3b6ee3b8...caf53785 - 5 commits from branch master
• 01572282 - daemon/tls: fix a double-free for some cases of policy.TLS_FORWARD

Compare with previous version

merged

mentioned in commit 4ec39892