Replace Curl_resolv_unlock() with Curl_resolv_unlink():
-replace inuse member with refcount in Curl_dns_entry
- pass Curl_dns_entry ** to unlink, so it gets always cleared
- solve potential (but unlikley) UAF in FTP's handling of looked up
Curl_dns_entry. Esp. do not use addr information after unlinking an entry.
In reality, the unlink will not free memory, as the dns entry is still
referenced by the hostcache. But this is not safe and relying on no other
code pruning the cache in the meantime.
- pass permanent flag when adding a dns entry instead of fixing timestamp
afterwards.
url.c: fold several static *resolve_* functions into one.
Closes#14195
5a9262a333