curl: Use after free (read) in curl_multi_perform with DoH and Proxy options, and resolve timeouts

Summary: summary of the vulnerability There is a use after free in curlmultiperform when DoH resolver timeouts and CURLOPTPROXY is used see reproducer and stack trace I found it via fuzzing with https://github.com/catenacyber/curl-fuzzer/tree/proxy after fixing a small memory leak in curl Another...